Patent Publication Number: US-2023145330-A1

Title: Glucose estimation without continuous glucose monitoring

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of and claims the benefit of priority to U.S. patent application Ser. No. 17/178,087 entitled “MACHINE LEARNING-BASED SYSTEM FOR ESTIMATING GLUCOSE VALUES” and filed Feb. 17, 2021, which is a continuation of and claims the BENEFIT of priority to U.S. patent application Ser. No. 16/987,330 entitled “MACHINE LEARNING-BASED SYSTEM FOR ESTIMATING GLUCOSE VALUES” and filed Aug. 6, 2020, the each of which is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present technology is generally related to the medical arts and, more specifically, to glucose estimation without continuous glucose monitoring. 
     BACKGROUND 
     Portable medical devices are useful for patients that have conditions that must be monitored on a continuous or frequent basis. For example, diabetics are usually required to modify and monitor their daily lifestyle to keep their blood glucose (BG) in balance. Individuals with Type 1 diabetes and some individuals with Type 2 diabetes use insulin (and other blood sugar lowering medications) to control their BG levels. To maintain glucose levels within a recommended range, patients with diabetes are advised to routinely keep strict schedules, including ingesting timely nutritious meals, partaking in exercise, monitoring BG levels daily, and adjusting and administering insulin dosages accordingly. 
     Infusion pump devices and insulin pump systems are relatively well known in the medical arts. Infusion pump devices and insulin systems are designed to deliver accurate and measured doses of insulin via infusion sets. An infusion set delivers the insulin to a patient through a small diameter tube that terminates at, e.g., a cannula inserted under the patient&#39;s skin. Use of infusion pump therapy has been increasing, especially for delivering insulin for diabetics. 
     In one type of system, the infusion pump can be programmed to inject insulin on a set schedule. For instance, a doctor or other healthcare administrator can program an insulin pump according to a set schedule so that it delivers insulin into the patient&#39;s bloodstream according to that schedule throughout the day. In addition, the patient can also simply activate the insulin pump to administer an insulin bolus as needed, for example, in response to the patient&#39;s high BG level. One drawback to this approach is that the user&#39;s lack knowledge of their blood glucose levels in any given point, and it is difficult for patients to determine when it may be necessary to administer insulin outside their scheduled administrations. 
     To address this problem, a patient can monitor BG levels using a BG meter or measurement device. For instance, a patient can utilize a blood glucose meter to intermittently measure their instantaneous blood sugar levels at any given time via a “finger prick test.” Information from that measurement can be processed and used to determine whether insulin should be administered to regulate the patient&#39;s blood sugar level. A problem with this approach is that monitoring of blood glucose levels and the administration of insulin is done by the user on an ad hoc basis based on when they think insulin should be administered. This can be problematic in certain situations, such as with patients who experience hypoglycemia unawareness, which is a condition that can occur where a patient cannot perceive symptoms that might be indicators that their blood sugar is low. 
     To address this issue, continuous glucose monitoring (CGM) systems can be used to help diabetic patients continuously monitor their blood glucose levels. Continuous glucose monitoring systems employ a continuous glucose sensor to monitor a patient&#39;s blood glucose level in a substantially continuous and autonomous manner. In many cases, a continuous glucose monitoring sensor is utilized in conjunction with an insulin infusion device or insulin pump as parts of a digital diabetes management system. The digital diabetes management system can determine the amount of glucose in the patient&#39;s blood at any given time so that an appropriate amount of insulin can be automatically administered to help regulate the amount of glucose in the patient&#39;s blood. This way insulin can be automatically administered depending on the patient&#39;s specific needs such that their blood sugar levels do not go too high or too low at any particular time. This way, an equilibrium or balance can be achieved between entry of glucose into the body (e.g., the amount of glucose that is being introduced into the patient&#39;s blood stream via meals) and how much glucose is being consumed or utilized by the patient. 
     While existing continuous glucose monitoring systems that employ a continuous glucose sensor work well, such continuous glucose monitoring systems are often too expensive for potential users to afford. In some cases, a patient&#39;s insurance does not cover such therapy or the patient&#39;s insurance may refuse to pay for the patient to use such a solution if the patient does not fall within a high enough risk category to be covered for such therapy. In addition, some patients may simply choose not to utilize continuous glucose monitoring systems for lifestyle reasons. For instance, a particular user may choose not to wear a continuous glucose monitor or sensor arrangement because it could be uncomfortable, or they choose not to wear it all the time for other reasons. This can prevent a large group of users from using a digital diabetes management solution. 
     Today, a large segment of the diabetes market does not utilize CGM-type therapy devices. A substantial proportion of these users include, for example, users who rely on discrete blood glucose measurements several times a day to monitor glycemia (e.g., those using blood glucose meters), or users who intermittently wear a CGM under supervision of a health care provider (HCP). Without using a CGM device on a regular basis, these approaches can make it difficult for users to manage glycemia without actively making meaningful behavioral adjustments to improve their individual management. 
     Accordingly, it is desirable to provide digital diabetes management solutions that are less expensive and can thus be an option for users who are unable to afford more expensive continuous glucose monitoring systems. It would be desirable to provide users with alternative solutions that can achieve the same or similar benefits of full CGM-type therapy solutions without requiring users to wear a CGM device on a regular basis and without requiring users to absorb the costs associated with wearing a CGM device on a regular basis. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background. 
     BRIEF SUMMARY 
     Disclosed herein are techniques related to glucose estimation without continuous glucose monitoring. The techniques may be practiced using a processor-implemented method; a system comprising one or more processors and one or more processor-readable media; and/or one or more non-transitory processor-readable media. 
     In some embodiments, the techniques may involve receiving input data associated with a user. The input data may comprise discrete blood glucose measurement data associated with the user, activity data associated with the user, contextual data associated with the user, or a combination thereof. The techniques may also involve using an estimation model and the input data associated with the user to generate one or more estimated blood glucose values associated with the user. 
     This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. The details of one or more aspects of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the techniques described in this disclosure will be apparent from the description and drawings, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is an exemplary embodiment of an infusion system; 
         FIG.  2    is a plan view of an exemplary embodiment of a fluid infusion device suitable for use in the infusion system of  FIG.  1   ; 
         FIG.  3    is an exploded perspective view of the fluid infusion device of  FIG.  2   ; 
         FIG.  4    is a cross-sectional view of the fluid infusion device of  FIGS.  2 - 3    as viewed along line  4 - 4  in  FIG.  3    when assembled with a reservoir inserted in the infusion device; 
         FIG.  5    is a block diagram of an exemplary infusion system suitable for use with a fluid infusion device in one or more embodiments; 
         FIG.  6    is a block diagram of an exemplary pump control system suitable for use in the infusion device in the infusion system of  FIG.  5    in one or more embodiments; 
         FIG.  7    is a block diagram of a closed-loop control system that may be implemented or otherwise supported by the pump control system in the fluid infusion device of  FIGS.  5 - 6    in one or more exemplary embodiments; 
         FIG.  8    is a block diagram of an exemplary patient monitoring system; 
         FIG.  9    is a simplified block diagram representation of an exemplary embodiment of a computer-based or processor-based device suitable for deployment in the system shown in  FIG.  1   ; 
         FIG.  10    is a block diagram of a system for estimating glucose values for a particular user or patient in accordance with the disclosed embodiments; 
         FIG.  11    is a flowchart that illustrates a method for generating an estimation model for a particular patient in accordance with the disclosed embodiments; 
         FIG.  12    is a flowchart of a method in accordance with the disclosed embodiments; 
         FIG.  13    is a block diagram of a workflow process for generating a personalized model that is optimized for estimating glucose values for a particular user or patient in accordance with the disclosed embodiments; 
         FIG.  14    is a block diagram of a machine learning system for generating an optimized population model for estimating glucose values for a population of users or patients in accordance with the disclosed embodiments; 
         FIG.  15    is a block diagram of a windowed machine learning system for generating an optimized window population model for estimating glucose values for a population of users or patients in accordance with the disclosed embodiments; 
         FIG.  16    is a block diagram of another windowed machine learning system for generating an optimized window population model for estimating glucose values for a population of users or patients in accordance with the disclosed embodiments; 
         FIG.  17    is a block diagram of another windowed machine learning system for generating an optimized window population model for estimating glucose values for a population of users or patients in accordance with the disclosed embodiments; 
         FIG.  18    is a block diagram of another windowed machine learning system for generating an optimized window population model for estimating glucose values for a population of users or patients in accordance with the disclosed embodiments; 
         FIG.  19    is a block diagram of another windowed machine learning system for generating an optimized window population model for estimating glucose values for a population of users or patients in accordance with the disclosed embodiments; 
         FIG.  20    is a block diagram of a model explainability analysis processor for selecting an optimized population model for estimating glucose values for a population of users or patients in accordance with the disclosed embodiments; 
         FIG.  21    is a block diagram of a calibration optimization processor for selecting an optimized calibration model in accordance with the disclosed embodiments; 
         FIG.  22    is a block diagram of a calibration optimization processor for selecting optimal type(s) of inputs to be used for developing an optimized calibration model in accordance with the disclosed embodiments; 
         FIG.  23    is a block diagram of a machine learning system for generating an optimized personal model for estimating glucose values that are personalized for a particular user or patient in accordance with the disclosed embodiments; 
         FIG.  24    is a block diagram of a windowed machine learning system for generating an optimized personal model for estimating glucose values that are personalized for a particular user or patient in accordance with the disclosed embodiments; 
         FIG.  25    is a block diagram of another windowed machine learning system for generating an optimized personal model for estimating glucose values that are personalized for a particular user or patient in accordance with the disclosed embodiments; 
         FIG.  26    is a block diagram of another windowed machine learning system for generating an optimized personal model for estimating glucose values that are personalized for a particular user or patient in accordance with the disclosed embodiments; 
         FIG.  27    is a block diagram of another windowed machine learning system for generating an optimized personal model for estimating glucose values for a personalized a particular user or patient in accordance with the disclosed embodiments; 
         FIG.  28    is a block diagram that illustrates an intermittent CGM system in accordance with the disclosed embodiments; and 
         FIG.  29    is a block diagram that illustrates another intermittent CGM system in accordance with the disclosed embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description is merely illustrative in nature and is not intended to limit the embodiments of the subject matter or the application and uses of such embodiments. As used herein, the word “exemplary” means “serving as an example, instance, or illustration.” Any implementation described herein as exemplary is not necessarily to be construed as preferred or advantageous over other implementations. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description. 
     It should be understood that various aspects disclosed herein may be combined in different combinations than the combinations specifically presented in the description and accompanying drawings. It should also be understood that, depending on the example, certain acts or events of any of the processes or methods described herein may be performed in a different sequence, may be added, merged, or left out altogether (e.g., all described acts or events may not be necessary to carry out the techniques). In addition, while certain aspects of this disclosure are described as being performed by a single module or unit for purposes of clarity, it should be understood that the techniques of this disclosure may be performed by a combination of units or modules associated with, for example, a medical device. 
     In one or more examples, the described techniques may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions or code on a computer-readable medium and executed by a hardware-based processing unit. Computer-readable media may include non-transitory computer-readable media, which corresponds to a tangible medium such as data storage media (e.g., RAM, ROM, EEPROM, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer). 
     Instructions may be configurable to be executed by one or more processors, such as one or more digital signal processors (DSPs), general purpose microprocessors, application specific integrated circuits (ASICs), field programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuitry. Accordingly, the term “processor” as used herein may refer to any of the foregoing structure or any other physical structure suitable for implementation of the described techniques. Also, the techniques could be fully implemented in one or more circuits or logic elements. 
     Exemplary embodiments of the subject matter described herein are implemented in conjunction with medical devices, such as portable electronic medical devices. Although many different applications are possible, the following description focuses on embodiments that incorporate an insulin infusion device (or insulin pump) as part of an infusion system deployment. For the sake of brevity, conventional techniques related to infusion system operation, insulin pump and/or infusion set operation, and other functional aspects of the systems (and the individual operating components of the systems) may not be described in detail here. Examples of infusion pumps may be of the type described in, but not limited to, U.S. Pat. Nos. 4,562,751; 4,685,903; 5,080,653; 5,505,709; 5,097,122; 6,485,465; 6,554,798; 6,558,320; 6,558,351; 6,641,533; 6,659,980; 6,752,787; 6,817,990; 6,932,584; and 7,621,893; each of which are herein incorporated by reference. 
     Generally, a fluid infusion device includes a motor or other actuation arrangement that is operable to linearly displace a plunger (or stopper) of a fluid reservoir provided within the fluid infusion device to deliver a dosage of fluid, such as insulin, to the body of a user. Dosage commands that govern operation of the motor may be generated in an automated manner in accordance with the delivery control scheme associated with a particular operating mode, and the dosage commands may be generated in a manner that is influenced by a current (or most recent) measurement of a physiological condition in the body of the user. For example, in a closed-loop or automatic operating mode, dosage commands may be generated based on a difference between a current (or most recent) measurement of the interstitial fluid glucose level in the body of the user and a target (or reference) glucose setpoint value. In this regard, the rate of infusion may vary as the difference between a current measurement value and the target measurement value fluctuates. For purposes of explanation, the subject matter is described herein in the context of the infused fluid being insulin for regulating a glucose level of a user (or patient); however, it should be appreciated that many other fluids may be administered through infusion, and the subject matter described herein is not necessarily limited to use with insulin. 
     In one non-limiting embodiment, a method and system are provided for estimating glucose values based, for example, on data from a BG meter and an activity tracker. In other embodiments, other contextual information, such as food (including carbohydrate and macronutrient intake) can also be used to estimate glucose values (e.g., to reconstruct continuous glucose data). Machine learning-based estimation/prediction models can be developed off-line for each patient, or updated online for continuous learning, particularly during retraining periods of continuous glucose monitor (CGM) taking in current contextual data. Generic estimation/predication models can be built using patterns/instances from data collected from a similar cohort as the patient which provides a bigger data pool and hence larger scope for patient characterization. Because every person is different the estimation/prediction models are uniquely trained for each patient. 
     For example, a customized machine learning-based estimation/prediction model can be built for each patient during a training process using CGM data. The customized machine learning-based estimation/prediction model can then be invoked at run time based on finger-stick measurements entered by the user via a blood glucose meter in addition to other contextual information such as steps, heart rate, exercise, metabolic equivalents and other parameters collected from an activity tracker, and insulin and meal information from insulin pumps (or insulin pens) or user entries, while also taking into account their medical history and demographic information so that the predictions are not only personalized based on the individual&#39;s diabetes profile and behavior, but also equipped to account for deviations from a patient&#39;s regular routine. The customized machine learning-based estimation/prediction model can thus provide continuous current and predictive estimates of glucose levels in real-time using finger-stick measurements entered by the user via a blood glucose meter and including any of the other contextual information mentioned above. Also, because the contextual data for a patient can change over time, the estimation/prediction models can be updated on a regular basis. In other words, because a patient&#39;s condition can change over time, a patient can wear a continuous glucose sensor periodically (e.g., once or twice a month) to acquire data that can be used to retrain the estimation model so that it can generate more accurate estimates for that particular patient. 
     The functionality can reside, for example, both within a web-based application as well as a mobile application. The estimation models can be implemented/deployed at either a backend server that runs the estimation model as part of a web-based application and communicates information back to the user&#39;s phone, insulin pump or other end device, and/or can also implemented as part of a mobile application that runs on the user&#39;s phone or other end device and communicates information back to the insulin pump or other end device. The estimation models can also be implemented/deployed at an insulin pump. Regardless of the implementation, the applications can send push notifications to the patient to alert them in case of an estimated low or high excursion event, can receive requests from user and deliver precise, coherent answers, and can also provide a pathway for entering data which can be used to keep track of the user history as well as improve the prediction estimates. 
     The estimation model can be trained using a continuous glucose sensor device, and once it is trained and then personalized/tuned for a particular user/patient, the continuous glucose sensor does not need to be used on a regular basis. This can allow users/patients to rely less on a continuous glucose sensor. They only need to use a CGM periodically instead of on a regular basis. 
     Instead, a blood glucose meter can be used in conjunction with an activity tracker to generate inputs to the estimation model, and the estimation model can then generate estimated glucose values that approximate measured glucose values that would be measured by a continuous glucose sensor. In essence, the disclosed embodiments can allow a patient to use an activity tracker and intermittent measurements from a blood glucose meter without needing a continuous glucose sensor on a regular basis (e.g., the patient can use a continuous glucose sensor periodically for calibration, but then only use a blood glucose meter and an activity tracker in conjunction with an estimation model the remainder of the time). 
     In some embodiments, additional types of data can be processed by the estimation model, which can improve the accuracy of the estimates. For example, a patient can estimate their glucose values using meal data that describes what the patient has recently eaten, intermittent blood glucose measurements from a blood glucose meter (that are taken by a user, for example, via finger stick measurements), and other contextual activity data that is received on a continuous basis from an activity tracker or other source of activity information about the patient. This other contextual activity data can include data such as physical activity data (e.g., heart rate, number of steps, or metabolic equivalents, etc.), metabolic data (e.g., calories burned), etc. This information can be used via an estimation or predication module to estimate glucose values in a way that approximates, with high accuracy, blood glucose measurements that would be measured by a continuous glucose sensor without having to incur the cost of, or permanently attach, a continuous glucose sensor. When the estimated glucose values are accurate enough, they can be used, for example, to drive an insulin infusion device so that it administers insulin to a patient, or to provide notifications to a patient or health care partner to manually inject a bolus of insulin on an as needed basis depending on their estimated glucose values and other information such as activity data, meal information, etc., or alternatively to provide health care providers with information to adjust basal rate settings of an inulin infusion device so that they are appropriate for a particular patient to meet their needs. It may also be used as a medication titration advisor for individuals on other types of blood sugar lowering medications. When the estimated glucose values are not accurate enough, then this condition can be used to trigger a notification, warning, alarm or alert, for example, at another device such as at the insulin pump, the user&#39;s smartphone or other smart device, etc. to inform the user that they should not trust the system and to recommend that the user to wear another sensor (e.g., CGM) to retrain the estimation model. 
     Thus, the proposed method and system can provide a new digital diabetes management solution that is cheaper and more affordable; more likely to be used by users who are unable to afford digital diabetes management systems; more likely to be approved by insurance, etc. The proposed method and system can also help users start using a digital diabetes management solution until they transition to a CGM-based system for diabetes management. 
     Turning now to  FIG.  1   , one exemplary embodiment of an infusion system  100  includes, without limitation, a fluid infusion device (or infusion pump)  102 , a sensing arrangement  104 , a command control device (CCD)  106 , and a computer  108 . The components of an infusion system  100  may be realized using different platforms, designs, and configurations, and the embodiment shown in  FIG.  1    is not exhaustive or limiting. In practice, the infusion device  102  and the sensing arrangement  104  are secured at desired locations on the body of a user (or patient), as illustrated in  FIG.  1   . In this regard, the locations at which the infusion device  102  and the sensing arrangement  104  are secured to the body of the user in  FIG.  1    are provided only as a representative, non-limiting, example. The elements of the infusion system  100  may be similar to those described in U.S. Pat. No. 8,674,288, the subject matter of which is hereby incorporated by reference in its entirety. 
     In the illustrated embodiment of  FIG.  1   , the infusion device  102  is designed as a portable medical device suitable for infusing a fluid, a liquid, a gel, or other medicament into the body of a user. In exemplary embodiments, the infused fluid is insulin, although many other fluids may be administered through infusion such as, but not limited to, HIV drugs, drugs to treat pulmonary hypertension, iron chelation drugs, pain medications, anti-cancer treatments, medications, vitamins, hormones, or the like. In some embodiments, the fluid may include a nutritional supplement, a dye, a tracing medium, a saline medium, a hydration medium, or the like. 
     The sensing arrangement  104  generally represents the components of the infusion system  100  configured to sense, detect, measure or otherwise quantify a condition of the user, and may include a sensor, a monitor, or the like, for providing data indicative of the condition that is sensed, detected, measured or otherwise monitored by the sensing arrangement. In this regard, the sensing arrangement  104  may include electronics and enzymes reactive to a biological condition, such as a blood glucose level, or the like, of the user, and provide data indicative of the blood glucose level to the infusion device  102 , the CCD  106  and/or the computer  108 . For example, the infusion device  102 , the CCD  106  and/or the computer  108  may include a display for presenting information or data to the user based on the sensor data received from the sensing arrangement  104 , such as, for example, a current glucose level of the user, a graph or chart of the user&#39;s glucose level versus time, device status indicators, alert messages, or the like. In other embodiments, the infusion device  102 , the CCD  106  and/or the computer  108  may include electronics and software that are configured to analyze sensor data and operate the infusion device  102  to deliver fluid to the body of the user based on the sensor data and/or preprogrammed delivery routines. Thus, in exemplary embodiments, one or more of the infusion device  102 , the sensing arrangement  104 , the CCD  106 , and/or the computer  108  includes a transmitter, a receiver, and/or other transceiver electronics that allow for communication with other components of the infusion system  100 , so that the sensing arrangement  104  may transmit sensor data or monitor data to one or more of the infusion device  102 , the CCD  106  and/or the computer  108 . 
     Still referring to  FIG.  1   , in various embodiments, the sensing arrangement  104  may be secured to the body of the user or embedded in the body of the user at a location that is remote from the location at which the infusion device  102  is secured to the body of the user. In various other embodiments, the sensing arrangement  104  may be incorporated within the infusion device  102 . In other embodiments, the sensing arrangement  104  may be separate and apart from the infusion device  102 , and may be, for example, part of the CCD  106 . In such embodiments, the sensing arrangement  104  may be configured to receive a biological sample, analyte, or the like, to measure a condition of the user. 
     In some embodiments, the CCD  106  and/or the computer  108  may include electronics and other components configured to perform processing, delivery routine storage, and to control the infusion device  102  in a manner that is influenced by sensor data measured by and/or received from the sensing arrangement  104 . By including control functions in the CCD  106  and/or the computer  108 , the infusion device  102  may be made with more simplified electronics. However, in other embodiments, the infusion device  102  may include all control functions, and may operate without the CCD  106  and/or the computer  108 . In various embodiments, the CCD  106  may be a portable electronic device. In addition, in various embodiments, the infusion device  102  and/or the sensing arrangement  104  may be configured to transmit data to the CCD  106  and/or the computer  108  for display or processing of the data by the CCD  106  and/or the computer  108 . 
     In some embodiments, the CCD  106  and/or the computer  108  may provide information to the user that facilitates the user&#39;s subsequent use of the infusion device  102 . For example, the CCD  106  may provide information to the user to allow the user to determine the rate or dose of medication to be administered into the user&#39;s body. In other embodiments, the CCD  106  may provide information to the infusion device  102  to autonomously control the rate or dose of medication administered into the body of the user. In some embodiments, the sensing arrangement  104  may be integrated into the CCD  106 . Such embodiments may allow the user to monitor a condition by providing, for example, a sample of his or her blood to the sensing arrangement  104  to assess his or her condition. In some embodiments, the sensing arrangement  104  and the CCD  106  may be used for determining glucose levels in the blood and/or body fluids of the user without the use of, or necessity of, a wire or cable connection between the infusion device  102  and the sensing arrangement  104  and/or the CCD  106 . 
     In some embodiments, the sensing arrangement  104  and/or the infusion device  102  are cooperatively configured to utilize a closed-loop system for delivering fluid to the user. Examples of sensing devices and/or infusion pumps utilizing closed-loop systems may be found at, but are not limited to, the following U.S. Pat. Nos. 6,088,608, 6,119,028, 6,589,229, 6,740,072, 6,827,702, 7,323,142, and 7,402,153 or United States Patent Application Publication No. 2014/0066889, all of which are incorporated herein by reference in their entirety. In such embodiments, the sensing arrangement  104  is configured to sense or measure a condition of the user, such as, blood glucose level or the like. The infusion device  102  is configured to deliver fluid in response to the condition sensed by the sensing arrangement  104 . In turn, the sensing arrangement  104  continues to sense or otherwise quantify a current condition of the user, thereby allowing the infusion device  102  to deliver fluid continuously in response to the condition currently (or most recently) sensed by the sensing arrangement  104  indefinitely. In some embodiments, the sensing arrangement  104  and/or the infusion device  102  may be configured to utilize the closed-loop system only for a portion of the day, for example only when the user is asleep or awake. 
       FIGS.  2 - 4    depict one exemplary embodiment of a fluid infusion device  200  (or alternatively, infusion pump) suitable for use in an infusion system, such as, for example, as infusion device  102  in the infusion system  100  of  FIG.  1   . The fluid infusion device  200  is a portable medical device designed to be carried or worn by a patient (or user), and the fluid infusion device  200  may leverage any number of conventional features, components, elements, and characteristics of existing fluid infusion devices, such as, for example, some of the features, components, elements, and/or characteristics described in U.S. Pat. Nos. 6,485,465 and 7,621,893. It should be appreciated that  FIGS.  2 - 4    depict some aspects of the infusion device  200  in a simplified manner; in practice, the infusion device  200  could include additional elements, features, or components that are not shown or described in detail herein. 
     As best illustrated in  FIGS.  2 - 3   , the illustrated embodiment of the fluid infusion device  200  includes a housing  202  adapted to receive a fluid-containing reservoir  205 . An opening  220  in the housing  202  accommodates a fitting  223  (or cap) for the reservoir  205 , with the fitting  223  being configured to mate or otherwise interface with tubing  221  of an infusion set  225  that provides a fluid path to/from the body of the user. In this manner, fluid communication from the interior of the reservoir  205  to the user is established via the tubing  221 . The illustrated fluid infusion device  200  includes a human-machine interface (HMI)  230  (or user interface) that includes elements  232 ,  234  that can be manipulated by the user to administer a bolus of fluid (e.g., insulin), to change therapy settings, to change user preferences, to select display features, and the like. The infusion device also includes a display element  226 , such as a liquid crystal display (LCD) or another suitable display element, that can be used to present various types of information or data to the user, such as, without limitation: the current glucose level of the patient; the time; a graph or chart of the patient&#39;s glucose level versus time; device status indicators; etc. 
     The housing  202  is formed from a substantially rigid material having a hollow interior  214  adapted to allow an electronics assembly  204 , a sliding member (or slide)  206 , a drive system  208 , a sensor assembly  210 , and a drive system capping member  212  to be disposed therein in addition to the reservoir  205 , with the contents of the housing  202  being enclosed by a housing capping member  216 . The opening  220 , the slide  206 , and the drive system  208  are coaxially aligned in an axial direction (indicated by arrow  218 ), whereby the drive system  208  facilitates linear displacement of the slide  206  in the axial direction  218  to dispense fluid from the reservoir  205  (after the reservoir  205  has been inserted into opening  220 ), with the sensor assembly  210  being configured to measure axial forces (e.g., forces aligned with the axial direction  218 ) exerted on the sensor assembly  210  responsive to operating the drive system  208  to displace the slide  206 . In various embodiments, the sensor assembly  210  may be utilized to detect one or more of the following: an occlusion in a fluid path that slows, prevents, or otherwise degrades fluid delivery from the reservoir  205  to a user&#39;s body; when the reservoir  205  is empty; when the slide  206  is properly seated with the reservoir  205 ; when a fluid dose has been delivered; when the infusion device  200  is subjected to shock or vibration; when the infusion device  200  requires maintenance. 
     Depending on the embodiment, the fluid-containing reservoir  205  may be realized as a syringe, a vial, a cartridge, a bag, or the like. In certain embodiments, the infused fluid is insulin, although many other fluids may be administered through infusion such as, but not limited to, HIV drugs, drugs to treat pulmonary hypertension, iron chelation drugs, pain medications, anti-cancer treatments, medications, vitamins, hormones, or the like. As best illustrated in  FIGS.  3 - 4   , the reservoir  205  typically includes a reservoir barrel  219  that contains the fluid and is concentrically and/or coaxially aligned with the slide  206  (e.g., in the axial direction  218 ) when the reservoir  205  is inserted into the infusion device  200 . The end of the reservoir  205  proximate the opening  220  may include or otherwise mate with the fitting  223 , which secures the reservoir  205  in the housing  202  and prevents displacement of the reservoir  205  in the axial direction  218  with respect to the housing  202  after the reservoir  205  is inserted into the housing  202 . As described above, the fitting  223  extends from (or through) the opening  220  of the housing  202  and mates with tubing  221  to establish fluid communication from the interior of the reservoir  205  (e.g., reservoir barrel  219 ) to the user via the tubing  221  and infusion set  225 . The opposing end of the reservoir  205  proximate the slide  206  includes a plunger  217  (or stopper) positioned to push fluid from inside the barrel  219  of the reservoir  205  along a fluid path through tubing  221  to a user. The slide  206  is configured to mechanically couple or otherwise engage with the plunger  217 , thereby becoming seated with the plunger  217  and/or reservoir  205 . Fluid is forced from the reservoir  205  via tubing  221  as the drive system  208  is operated to displace the slide  206  in the axial direction  218  toward the opening  220  in the housing  202 . 
     In the illustrated embodiment of  FIGS.  3 - 4   , the drive system  208  includes a motor assembly  207  and a drive screw  209 . The motor assembly  207  includes a motor that is coupled to drive train components of the drive system  208  that are configured to convert rotational motor motion to a translational displacement of the slide  206  in the axial direction  218 , and thereby engaging and displacing the plunger  217  of the reservoir  205  in the axial direction  218 . In some embodiments, the motor assembly  207  may also be powered to translate the slide  206  in the opposing direction (e.g., the direction opposite direction  218 ) to retract and/or detach from the reservoir  205  to allow the reservoir  205  to be replaced. In exemplary embodiments, the motor assembly  207  includes a brushless DC (BLDC) motor having one or more permanent magnets mounted, affixed, or otherwise disposed on its rotor. However, the subject matter described herein is not necessarily limited to use with BLDC motors, and in alternative embodiments, the motor may be realized as a solenoid motor, an AC motor, a stepper motor, a piezoelectric caterpillar drive, a shape memory actuator drive, an electrochemical gas cell, a thermally driven gas cell, a bimetallic actuator, or the like. The drive train components may comprise one or more lead screws, cams, ratchets, jacks, pulleys, pawls, clamps, gears, nuts, slides, bearings, levers, beams, stoppers, plungers, sliders, brackets, guides, bearings, supports, bellows, caps, diaphragms, bags, heaters, or the like. In this regard, although the illustrated embodiment of the infusion pump utilizes a coaxially aligned drive train, the motor could be arranged in an offset or otherwise non-coaxial manner, relative to the longitudinal axis of the reservoir  205 . 
     As best shown in  FIG.  4   , the drive screw  209  mates with threads  402  internal to the slide  206 . When the motor assembly  207  is powered and operated, the drive screw  209  rotates, and the slide  206  is forced to translate in the axial direction  218 . In an exemplary embodiment, the infusion device  200  includes a sleeve  211  to prevent the slide  206  from rotating when the drive screw  209  of the drive system  208  rotates. Thus, rotation of the drive screw  209  causes the slide  206  to extend or retract relative to the drive motor assembly  207 . When the fluid infusion device is assembled and operational, the slide  206  contacts the plunger  217  to engage the reservoir  205  and control delivery of fluid from the infusion device  200 . In an exemplary embodiment, the shoulder portion  215  of the slide  206  contacts or otherwise engages the plunger  217  to displace the plunger  217  in the axial direction  218 . In alternative embodiments, the slide  206  may include a threaded tip  213  capable of being detachably engaged with internal threads  404  on the plunger  217  of the reservoir  205 , as described in detail in U.S. Pat. Nos. 6,248,093 and 6,485,465, which are incorporated by reference herein. 
     As illustrated in  FIG.  3   , the electronics assembly  204  includes control electronics  224  coupled to the display element  226 , with the housing  202  including a transparent window portion  228  that is aligned with the display element  226  to allow the display element  226  to be viewed by the user when the electronics assembly  204  is disposed within the interior  214  of the housing  202 . The control electronics  224  generally represent the hardware, firmware, processing logic and/or software (or combinations thereof) configured to control operation of the motor assembly  207  and/or drive system  208 , as described in greater detail below in the context of  FIG.  5   . The control electronics  224  is also suitably configured and designed to support various user interface, input/output, and display features of the fluid infusion device  200 . Whether such functionality is implemented as hardware, firmware, a state machine, or software depends upon the particular application and design constraints imposed on the embodiment. Those familiar with the concepts described here may implement such functionality in a suitable manner for each particular application, but such implementation decisions should not be interpreted as being restrictive or limiting. In an exemplary embodiment, the control electronics  224  includes one or more programmable controllers that may be programmed to control operation of the infusion device  200 . 
     The motor assembly  207  includes one or more electrical leads  236  adapted to be electrically coupled to the electronics assembly  204  to establish communication between the control electronics  224  and the motor assembly  207 . In response to command signals from the control electronics  224  that operate a motor driver (e.g., a power converter) to regulate the amount of power supplied to the motor from a power supply, the motor actuates the drive train components of the drive system  208  to displace the slide  206  in the axial direction  218  to force fluid from the reservoir  205  along a fluid path (including tubing  221  and an infusion set), thereby administering doses of the fluid contained in the reservoir  205  into the user&#39;s body. Preferably, the power supply is realized one or more batteries contained within the housing  202 . Alternatively, the power supply may be a solar panel, capacitor, AC or DC power supplied through a power cord, or the like. In some embodiments, the control electronics  224  may operate the motor of the motor assembly  207  and/or drive system  208  in a stepwise manner, typically on an intermittent basis; to administer discrete precise doses of the fluid to the user according to programmed delivery profiles. 
     Referring to  FIGS.  2 - 4   , as described above, the user interface  230  includes HMI elements, such as buttons  232  and a directional pad  234 , that are formed on a graphic keypad overlay  231  that overlies a keypad assembly  233 , which includes features corresponding to the buttons  232 , directional pad  234  or other user interface items indicated by the graphic keypad overlay  231 . When assembled, the keypad assembly  233  is coupled to the control electronics  224 , thereby allowing the HMI elements  232 ,  234  to be manipulated by the user to interact with the control electronics  224  and control operation of the infusion device  200 , for example, to administer a bolus of insulin, to change therapy settings, to change user preferences, to select display features, to set or disable alarms and reminders, and the like. In this regard, the control electronics  224  maintains and/or provides information to the display element  226  regarding program parameters, delivery profiles, pump operation, alarms, warnings, statuses, or the like, which may be adjusted using the HMI elements  232 ,  234 . In various embodiments, the HMI elements  232 ,  234  may be realized as physical objects (e.g., buttons, knobs, joysticks, and the like) or virtual objects (e.g., using touch-sensing and/or proximity-sensing technologies). For example, in some embodiments, the display element  226  may be realized as a touch screen or touch-sensitive display, and in such embodiments, the features and/or functionality of the HMI elements  232 ,  234  may be integrated into the display element  226  and the HMI  230  may not be present. In some embodiments, the electronics assembly  204  may also include alert generating elements coupled to the control electronics  224  and suitably configured to generate one or more types of feedback, such as, without limitation: audible feedback; visual feedback; haptic (physical) feedback; or the like. 
     Referring to  FIGS.  3 - 4   , in accordance with one or more embodiments, the sensor assembly  210  includes a back plate structure  250  and a loading element  260 . The loading element  260  is disposed between the capping member  212  and a beam structure  270  that includes one or more beams having sensing elements disposed thereon that are influenced by compressive force applied to the sensor assembly  210  that deflects the one or more beams, as described in greater detail in U.S. Pat. No. 8,474,332, which is incorporated by reference herein. In exemplary embodiments, the back plate structure  250  is affixed, adhered, mounted, or otherwise mechanically coupled to the bottom surface  238  of the drive system  208  such that the back plate structure  250  resides between the bottom surface  238  of the drive system  208  and the housing capping member  216 . The drive system capping member  212  is contoured to accommodate and conform to the bottom of the sensor assembly  210  and the drive system  208 . The drive system capping member  212  may be affixed to the interior of the housing  202  to prevent displacement of the sensor assembly  210  in the direction opposite the direction of force provided by the drive system  208  (e.g., the direction opposite direction  218 ). Thus, the sensor assembly  210  is positioned between the motor assembly  207  and secured by the capping member  212 , which prevents displacement of the sensor assembly  210  in a downward direction opposite the direction of the arrow that represents the axial direction  218 , such that the sensor assembly  210  is subjected to a reactionary compressive force when the drive system  208  and/or motor assembly  207  is operated to displace the slide  206  in the axial direction  218  in opposition to the fluid pressure in the reservoir  205 . Under normal operating conditions, the compressive force applied to the sensor assembly  210  is correlated with the fluid pressure in the reservoir  205 . As shown, electrical leads  240  are adapted to electrically couple the sensing elements of the sensor assembly  210  to the electronics assembly  204  to establish communication to the control electronics  224 , wherein the control electronics  224  are configured to measure, receive, or otherwise obtain electrical signals from the sensing elements of the sensor assembly  210  that are indicative of the force applied by the drive system  208  in the axial direction  218 . 
       FIG.  5    depicts an exemplary embodiment of an infusion system  500  suitable for use with an infusion device  502 , such as any one of the infusion devices  102 ,  200  described above. The infusion system  500  is capable of controlling or otherwise regulating a physiological condition in the body  501  of a patient to a desired (or target) value or otherwise maintain the condition within a range of acceptable values in an automated or autonomous manner. In one or more exemplary embodiments, the condition being regulated is sensed, detected, measured or otherwise quantified by a sensing arrangement  504  (e.g., a blood glucose sensing arrangement  504 ) communicatively coupled to the infusion device  502 . However, it should be noted that in alternative embodiments, the condition being regulated by the infusion system  500  may be correlative to the measured values obtained by the sensing arrangement  504 . That said, for clarity and purposes of explanation, the subject matter may be described herein in the context of the sensing arrangement  504  being realized as a glucose sensing arrangement that senses, detects, measures or otherwise quantifies the patient&#39;s glucose level, which is being regulated in the body  501  of the patient by the infusion system  500 . 
     In exemplary embodiments, the sensing arrangement  504  includes one or more interstitial glucose sensing elements that generate or otherwise output electrical signals (alternatively referred to herein as measurement signals) having a signal characteristic that is correlative to, influenced by, or otherwise indicative of the relative interstitial fluid glucose level in the body  501  of the patient. The output electrical signals are filtered or otherwise processed to obtain a measurement value indicative of the patient&#39;s interstitial fluid glucose level. For example, in one implementation, a sensor of the continuous glucose monitor (CGM) measures glucose indirectly via interstitial fluid using, e.g., a subcutaneous sensor. Interstitial fluid is the fluid that surrounds the cells of the patient&#39;s tissue below their skin, and usually glucose moves from their blood vessels and capillaries first and then into their interstitial fluid. Thus, sensor glucose readings are taken by the sensing arrangement  504  from the patient&#39;s interstitial fluid, and not from their blood, like finger stick measurements. For purposes of explanation, the calibrated blood glucose values that are calculated based on the electrical signals output by the sensing element(s) of the sensing arrangement  504  may alternatively be referred to herein as the sensor glucose (SG) value, the sensed glucose value, or variants thereof. There is a physiological lag between measurements of interstitial SG values versus blood glucose values. As such, in most cases the sensing arrangement  504  needs to be calibrated using a blood glucose meter  530 . To explain further, the blood glucose meter  530  measures blood glucose values directly from a blood stream. As such, blood glucose values can refer to glucose values measured directly from a supply of a patient&#39;s blood. In this regard, the terms “blood glucose measurement,” “measured blood glucose,” “blood glucose concentration,” “measured blood glucose concentration,” and the like may refer to a glucose level, a blood glucose level, a blood glucose concentration, or the like, that has been obtained via any type of glucose sensor. In exemplary embodiments, a blood glucose meter  530 , such as a finger stick device, is utilized to directly sense, detect, measure or otherwise quantify the blood glucose in the body  501  of the patient. In this regard, the blood glucose meter  530  outputs or otherwise provides a measured blood glucose value that may be utilized as a reference measurement for calibrating the sensing arrangement  504  and converting a measurement value indicative of the patient&#39;s interstitial fluid glucose level into a corresponding calibrated blood glucose value. 
     In exemplary embodiments, the infusion system  500  also includes one or more additional sensing arrangements  506 ,  508  configured to sense, detect, measure or otherwise quantify a characteristic of the body  501  of the patient that is indicative of a condition in the body  501  of the patient. In this regard, in addition to the glucose sensing arrangement  504 , one or more auxiliary sensing arrangements  506  (also referred to herein as a source of activity data or “activity tracker”) may be worn, carried, or otherwise associated with the body  501  of the patient to measure characteristics or conditions of the patient (or the patient&#39;s activity) that may influence the patient&#39;s glucose levels or insulin sensitivity. For example, a heart rate sensing arrangement  506  could be worn on or otherwise associated with the patient&#39;s body  501  to sense, detect, measure or otherwise quantify the patient&#39;s heart rate, which, in turn, may be indicative of exercise (and the intensity thereof) that is likely to influence the patient&#39;s glucose levels or insulin response in the body  501 . In yet another embodiment, another invasive, interstitial, or subcutaneous sensing arrangement  506  may be inserted into the body  501  of the patient to obtain measurements of another physiological condition that may be indicative of exercise (and the intensity thereof), such as, for example, a lactate sensor, a ketone sensor, or the like. Depending on the embodiment, the auxiliary sensing arrangement(s)  506  could be realized as a standalone component worn by the patient, or alternatively, the auxiliary sensing arrangement(s)  506  may be integrated with the infusion device  502  or the glucose sensing arrangement  504 . 
     The illustrated infusion system  500  also includes an acceleration sensing arrangement  508  (or accelerometer) that may be worn on or otherwise associated with the patient&#39;s body  501  to sense, detect, measure or otherwise quantify an acceleration of the patient&#39;s body  501 , which, in turn, may be indicative of exercise or some other condition in the body  501  that is likely to influence the patient&#39;s insulin response. While the acceleration sensing arrangement  508  is depicted as being integrated into the infusion device  502  in  FIG.  5   , in alternative embodiments, the acceleration sensing arrangement  508  may be integrated with another sensing arrangement  504 ,  506  on the body  501  of the patient, or the acceleration sensing arrangement  508  may be realized as a separate standalone component that is worn by the patient. 
     In the illustrated embodiment, the pump control system  520  generally represents the electronics and other components of the infusion device  502  that control operation of the fluid infusion device  502  according to a desired infusion delivery program in a manner that is influenced by the sensed glucose value indicating the current glucose level in the body  501  of the patient. For example, to support a closed-loop operating mode, the pump control system  520  maintains, receives, or otherwise obtains a target or commanded glucose value, and automatically generates or otherwise determines dosage commands for operating an actuation arrangement, such as a motor  532 , to displace the plunger  517  and deliver insulin to the body  501  of the patient based on the difference between the sensed glucose value and the target glucose value. In other operating modes, the pump control system  520  may generate or otherwise determine dosage commands configured to maintain the sensed glucose value below an upper glucose limit, above a lower glucose limit, or otherwise within a desired range of glucose values. In practice, the infusion device  502  may store or otherwise maintain the target value, upper and/or lower glucose limit(s), insulin delivery limit(s), and/or other glucose threshold value(s) in a data storage element accessible to the pump control system  520 . As described in greater detail, in one or more exemplary embodiments, the pump control system  520  automatically adjusts or adapts one or more parameters or other control information used to generate commands for operating the motor  532  in a manner that accounts for a likely change in the patient&#39;s glucose level or insulin response resulting from a meal, exercise, or other activity. 
     Still referring to  FIG.  5   , the target glucose value and other threshold glucose values utilized by the pump control system  520  may be received from an external component (e.g., CCD  106  and/or computing device  108 ) or be input by a patient via a user interface element  540  associated with the infusion device  502 . In practice, the one or more user interface element(s)  540  associated with the infusion device  502  typically include at least one input user interface element, such as, for example, a button, a keypad, a keyboard, a knob, a joystick, a mouse, a touch panel, a touchscreen, a microphone or another audio input device, and/or the like. Additionally, the one or more user interface element(s)  540  include at least one output user interface element, such as, for example, a display element (e.g., a light-emitting diode or the like), a display device (e.g., a liquid crystal display or the like), a speaker or another audio output device, a haptic feedback device, or the like, for providing notifications or other information to the patient. It should be noted that although  FIG.  5    depicts the user interface element(s)  540  as being separate from the infusion device  502 , in practice, one or more of the user interface element(s)  540  may be integrated with the infusion device  502 . Furthermore, in some embodiments, one or more user interface element(s)  540  are integrated with the sensing arrangement  504  in addition to and/or in alternative to the user interface element(s)  540  integrated with the infusion device  502 . The user interface element(s)  540  may be manipulated by the patient to operate the infusion device  502  to deliver correction boluses, adjust target and/or threshold values, modify the delivery control scheme or operating mode, and the like, as desired. 
     Still referring to  FIG.  5   , in the illustrated embodiment, the infusion device  502  includes a motor control module  512  coupled to a motor  532  (e.g., motor assembly  207 ) that is operable to displace a plunger  517  (e.g., plunger  217 ) in a reservoir (e.g., reservoir  205 ) and provide a desired amount of fluid to the body  501  of a patient. In this regard, displacement of the plunger  517  results in the delivery of a fluid, such as insulin, that is capable of influencing the patient&#39;s physiological condition to the body  501  of the patient via a fluid delivery path (e.g., via tubing  221  of an infusion set  225 ). A motor driver module  514  is coupled between an energy source  518  and the motor  532 . The motor control module  512  is coupled to the motor driver module  514 , and the motor control module  512  generates or otherwise provides command signals that operate the motor driver module  514  to provide current (or power) from the energy source  518  to the motor  532  to displace the plunger  517  in response to receiving, from a pump control system  520 , a dosage command indicative of the desired amount of fluid to be delivered. 
     In exemplary embodiments, the energy source  518  is realized as a battery housed within the infusion device  502  (e.g., within housing  202 ) that provides direct current (DC) power. In this regard, the motor driver module  514  generally represents the combination of circuitry, hardware and/or other electrical components configured to convert or otherwise transfer DC power provided by the energy source  518  into alternating electrical signals applied to respective phases of the stator windings of the motor  532  that result in current flowing through the stator windings that generates a stator magnetic field and causes the rotor of the motor  532  to rotate. The motor control module  512  is configured to receive or otherwise obtain a commanded dosage from the pump control system  520 , convert the commanded dosage to a commanded translational displacement of the plunger  517 , and command, signal, or otherwise operate the motor driver module  514  to cause the rotor of the motor  532  to rotate by an amount that produces the commanded translational displacement of the plunger  517 . For example, the motor control module  512  may determine an amount of rotation of the rotor required to produce translational displacement of the plunger  517  that achieves the commanded dosage received from the pump control system  520 . Based on the current rotational position (or orientation) of the rotor with respect to the stator that is indicated by the output of the rotor sensing arrangement  516 , the motor control module  512  determines the appropriate sequence of alternating electrical signals to be applied to the respective phases of the stator windings that should rotate the rotor by the determined amount of rotation from its current position (or orientation). In embodiments where the motor  532  is realized as a BLDC motor, the alternating electrical signals commutate the respective phases of the stator windings at the appropriate orientation of the rotor magnetic poles with respect to the stator and in the appropriate order to provide a rotating stator magnetic field that rotates the rotor in the desired direction. Thereafter, the motor control module  512  operates the motor driver module  514  to apply the determined alternating electrical signals (e.g., the command signals) to the stator windings of the motor  532  to achieve the desired delivery of fluid to the patient. 
     When the motor control module  512  is operating the motor driver module  514 , current flows from the energy source  518  through the stator windings of the motor  532  to produce a stator magnetic field that interacts with the rotor magnetic field. In some embodiments, after the motor control module  512  operates the motor driver module  514  and/or motor  532  to achieve the commanded dosage, the motor control module  512  ceases operating the motor driver module  514  and/or motor  532  until a subsequent dosage command is received. In this regard, the motor driver module  514  and the motor  532  enter an idle state during which the motor driver module  514  effectively disconnects or isolates the stator windings of the motor  532  from the energy source  518 . In other words, current does not flow from the energy source  518  through the stator windings of the motor  532  when the motor  532  is idle, and thus, the motor  532  does not consume power from the energy source  518  in the idle state, thereby improving efficiency. 
     Depending on the embodiment, the motor control module  512  may be implemented or realized with a general purpose processor, a microprocessor, a controller, a microcontroller, a state machine, a content addressable memory, an application specific integrated circuit, a field programmable gate array, any suitable programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof, designed to perform the functions described herein. In exemplary embodiments, the motor control module  512  includes or otherwise accesses a data storage element or memory, including any sort of random access memory (RAM), read only memory (ROM), flash memory, registers, hard disks, removable disks, magnetic or optical mass storage, or any other short or long term storage media or other non-transitory computer-readable medium, which is capable of storing programming instructions for execution by the motor control module  512 . The computer-executable programming instructions, when read and executed by the motor control module  512 , cause the motor control module  512  to perform or otherwise support the tasks, operations, functions, and processes described herein. 
     It should be appreciated that  FIG.  5    is a simplified representation of the infusion device  502  for purposes of explanation and is not intended to limit the subject matter described herein in any way. In this regard, depending on the embodiment, some features and/or functionality of the sensing arrangement  504  may implemented by or otherwise integrated into the pump control system  520 , or vice versa. Similarly, in practice, the features and/or functionality of the motor control module  512  may implemented by or otherwise integrated into the pump control system  520 , or vice versa. Furthermore, the features and/or functionality of the pump control system  520  may be implemented by control electronics  224  located in the fluid infusion device  502 , while in alternative embodiments, the pump control system  520  may be implemented by a remote computing device that is physically distinct and/or separate from the infusion device  502 , such as, for example, the CCD  106  or the computing device  108 . 
       FIG.  6    depicts an exemplary embodiment of a pump control system  600  suitable for use as the pump control system  520  in  FIG.  5    in accordance with one or more embodiments. The illustrated pump control system  600  includes, without limitation, a pump control module  602 , a communications interface  604 , and a data storage element (or memory)  606 . The pump control module  602  is coupled to the communications interface  604  and the memory  606 , and the pump control module  602  is suitably configured to support the operations, tasks, and/or processes described herein. In various embodiments, the pump control module  602  is also coupled to one or more user interface elements (e.g., user interface  230 ,  540 ) for receiving user inputs (e.g., target glucose values or other glucose thresholds) and providing notifications, alerts, or other therapy information to the patient. 
     The communications interface  604  generally represents the hardware, circuitry, logic, firmware and/or other components of the pump control system  600  that are coupled to the pump control module  602  and configured to support communications between the pump control system  600  and the various sensing arrangements  504 ,  506 ,  508 . In this regard, the communications interface  604  may include or otherwise be coupled to one or more transceiver modules capable of supporting wireless communications between the pump control system  520 ,  600  and the sensing arrangement  504 ,  506 ,  508 . For example, the communications interface  604  may be utilized to receive sensor measurement values or other measurement data from each sensing arrangement  504 ,  506 ,  508  in an infusion system  500 . In other embodiments, the communications interface  604  may be configured to support wired communications to/from the sensing arrangement(s)  504 ,  506 ,  508 . In various embodiments, the communications interface  604  may also support communications with another electronic device (e.g., CCD  106  and/or computer  108 ) in an infusion system (e.g., to upload sensor measurement values to a server or other computing device, receive control information from a server or other computing device, and the like). 
     The pump control module  602  generally represents the hardware, circuitry, logic, firmware and/or other component of the pump control system  600  that is coupled to the communications interface  604  and configured to determine dosage commands for operating the motor  532  to deliver fluid to the body  501  based on measurement data received from the sensing arrangements  504 ,  506 ,  508  and perform various additional tasks, operations, functions and/or operations described herein. For example, in exemplary embodiments, pump control module  602  implements or otherwise executes a command generation application  610  that supports one or more autonomous operating modes and calculates or otherwise determines dosage commands for operating the motor  532  of the infusion device  502  in an autonomous operating mode based at least in part on a current measurement value for a condition in the body  501  of the patient. For example, in a closed-loop operating mode, the command generation application  610  may determine a dosage command for operating the motor  532  to deliver insulin to the body  501  of the patient based at least in part on the current glucose measurement value most recently received from the sensing arrangement  504  to regulate the patient&#39;s blood glucose level to a target reference glucose value. Additionally, the command generation application  610  may generate dosage commands for boluses that are manually-initiated or otherwise instructed by a patient via a user interface element. 
     In exemplary embodiments, the pump control module  602  also implements or otherwise executes a personalization application  608  that is cooperatively configured to interact with the command generation application  610  to support adjusting dosage commands or control information dictating the manner in which dosage commands are generated in a personalized, patient-specific manner. In this regard, in some embodiments, based on correlations between current or recent measurement data and the current operational context relative to historical data associated with the patient, the personalization application  608  may adjust or otherwise modify values for one or more parameters utilized by the command generation application  610  when determining dosage commands, for example, by modifying a parameter value at a register or location in memory  606  referenced by the command generation application  610 . In yet other embodiments, the personalization application  608  may predict meals or other events or activities that are likely to be engaged in by the patient and output or otherwise provide an indication of the predicted patient behavior for confirmation or modification by the patient, which, in turn, may then be utilized to adjust the manner in which dosage commands are generated to regulate glucose in a manner that accounts for the patient&#39;s behavior in a personalized manner. 
     Still referring to  FIG.  6   , depending on the embodiment, the pump control module  602  may be implemented or realized with at least one general purpose processor device, a microprocessor, a controller, a microcontroller, a state machine, a content addressable memory, an application specific integrated circuit, a field programmable gate array, any suitable programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof, designed to perform the functions described herein. In this regard, the steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in firmware, in a software module executed by the pump control module  602 , or in any practical combination thereof. In exemplary embodiments, the pump control module  602  includes or otherwise accesses the data storage element or memory  606 , which may be realized using any sort of non-transitory computer-readable medium capable of storing programming instructions for execution by the pump control module  602 . The computer-executable programming instructions, when read and executed by the pump control module  602 , cause the pump control module  602  to implement or otherwise generate the applications  608 ,  610  and perform tasks, operations, functions, and processes described herein. 
     It should be understood that  FIG.  6    is a simplified representation of a pump control system  600  for purposes of explanation and is not intended to limit the subject matter described herein in any way. For example, in some embodiments, the features and/or functionality of the motor control module  512  may be implemented by or otherwise integrated into the pump control system  600  and/or the pump control module  602 , for example, by the command generation application  610  converting the dosage command into a corresponding motor command, in which case, the separate motor control module  512  may be absent from an embodiment of the infusion device  502 . 
       FIG.  7    depicts an exemplary closed-loop control system  700  that may be implemented by a pump control system  520 ,  600  to provide a closed-loop operating mode that autonomously regulates a condition in the body of a patient to a reference (or target) value. In this regard, the control system  700  can be utilized to regulate the delivery of insulin to the patient during an automatic basal insulin delivery operation. It should be appreciated that  FIG.  7    is a simplified representation of the control system  700  for purposes of explanation and is not intended to limit the subject matter described herein in any way. 
     In exemplary embodiments, the control system  700  receives or otherwise obtains a target glucose value at input  702 . In some embodiments, the target glucose value may be stored or otherwise maintained by the infusion device  502  (e.g., in memory  606 ), however, in some alternative embodiments, the target value may be received from an external component (e.g., CCD  106  and/or computer  108 ). In one or more embodiments, the target glucose value may be calculated or otherwise determined prior to entering the closed-loop operating mode based on one or more patient-specific control parameters. For example, the target blood glucose value may be calculated based at least in part on a patient-specific reference basal rate and a patient-specific daily insulin requirement, which are determined based on historical delivery information over a preceding interval of time (e.g., the amount of insulin delivered over the preceding 24 hours). The control system  700  also receives or otherwise obtains a current glucose measurement value (e.g., the most recently obtained sensor glucose value) from the sensing arrangement  504  at input  704 . The illustrated control system  700  implements or otherwise provides proportional-integral-derivative (PID) control to determine or otherwise generate delivery commands for operating the motor  532  based at least in part on the difference between the target glucose value and the current glucose measurement value. In this regard, the PID control attempts to minimize the difference between the measured value and the target value, and thereby regulates the measured value to the desired value. PID control parameters are applied to the difference between the target glucose level at input  702  and the measured glucose level at input  704  to generate or otherwise determine a dosage (or delivery) command provided at output  730 . Based on that delivery command, the motor control module  512  operates the motor  532  to deliver insulin to the body of the patient to influence the patient&#39;s glucose level, and thereby reduce the difference between a subsequently measured glucose level and the target glucose level. 
     The illustrated control system  700  includes or otherwise implements a summation block  706  configured to determine a difference between the target value obtained at input  702  and the measured value obtained from the sensing arrangement  504  at input  704 , for example, by subtracting the target value from the measured value. The output of the summation block  706  represents the difference between the measured and target values, which is then provided to each of a proportional term path, an integral term path, and a derivative term path. The proportional term path includes a gain block  720  that multiplies the difference by a proportional gain coefficient, K P , to obtain the proportional term. The integral term path includes an integration block  708  that integrates the difference and a gain block  722  that multiplies the integrated difference by an integral gain coefficient, K I , to obtain the integral term. The derivative term path includes a derivative block  710  that determines the derivative of the difference and a gain block  724  that multiplies the derivative of the difference by a derivative gain coefficient, K D , to obtain the derivative term. The proportional term, the integral term, and the derivative term are then added or otherwise combined to obtain a delivery command that is utilized to operate the motor at output  730 . Various implementation details pertaining to closed-loop PID control and determining gain coefficients are described in greater detail in U.S. Pat. No. 7,402,153, which is incorporated by reference. 
     In one or more exemplary embodiments, the PID gain coefficients are patient-specific and dynamically calculated or otherwise determined prior to entering the closed-loop operating mode based on historical insulin delivery information (e.g., amounts and/or timings of previous dosages, historical correction bolus information, or the like), historical sensor measurement values, historical reference blood glucose measurement values, user-reported or user-input events (e.g., meals, exercise, and the like), and the like. In this regard, one or more patient-specific control parameters (e.g., an insulin sensitivity factor, a daily insulin requirement, an insulin limit, a reference basal rate, a reference fasting glucose, an active insulin action duration, pharmodynamical time constants, or the like) may be utilized to compensate, correct, or otherwise adjust the PID gain coefficients to account for various operating conditions experienced and/or exhibited by the infusion device  502 . The PID gain coefficients may be maintained by the memory  606  accessible to the pump control module  602 . In this regard, the memory  606  may include a plurality of registers associated with the control parameters for the PID control. For example, a first parameter register may store the target glucose value and be accessed by or otherwise coupled to the summation block  706  at input  702 , and similarly, a second parameter register accessed by the proportional gain block  720  may store the proportional gain coefficient, a third parameter register accessed by the integration gain block  722  may store the integration gain coefficient, and a fourth parameter register accessed by the derivative gain block  724  may store the derivative gain coefficient. 
     In one or more exemplary embodiments, one or more parameters of the closed-loop control system  700  are automatically adjusted or adapted in a personalized manner to account for potential changes in the patient&#39;s glucose level or insulin sensitivity resulting from meals, exercise, or other events or activities. For example, in one or more embodiments, the target glucose value may be decreased in advance of a predicted meal event to achieve an increase in the insulin infusion rate to effectively pre-bolus a meal, and thereby reduce the likelihood of postprandial hyperglycemia. Additionally, or alternatively, the time constant or gain coefficient associated with one or more paths of the closed-loop control system  700  may be adjusted to tune the responsiveness to deviations between the measured glucose value and the target glucose value. For example, based on the particular type of meal being consumed or the particular time of day during which the meal is consumed, the time constant associated with the derivative block  710  or derivative term path may be adjusted to make the closed-loop control more or less aggressive in response to an increase in the patient&#39;s glucose level based on the patient&#39;s historical glycemic response to the particular type of meal. 
       FIG.  8    depicts an exemplary embodiment of a patient monitoring system  800 . The patient monitoring system  800  includes a medical device  802  that is communicatively coupled to a sensing element  804  that is inserted into the body of a patient or otherwise worn by the patient to obtain measurement data indicative of a physiological condition in the body of the patient, such as a sensed glucose level. The medical device  802  is communicatively coupled to a client device  806  via a communications network  810 , with the client device  806  being communicatively coupled to a remote device  814  via another communications network  812 . In this regard, the client device  806  may function as an intermediary for uploading or otherwise providing measurement data from the medical device  802  to the remote device  814 . It should be appreciated that  FIG.  8    depicts a simplified representation of a patient monitoring system  800  for purposes of explanation and is not intended to limit the subject matter described herein in any way. 
     In exemplary embodiments, the client device  806  is realized as a mobile phone, a smartphone, a tablet computer, or other similar mobile electronic device; however, in other embodiments, the client device  806  may be realized as any sort of electronic device capable of communicating with the medical device  802  via network  810 , such as a laptop or notebook computer, a desktop computer, or the like. In exemplary embodiments, the network  810  is realized as a Bluetooth network, a ZigBee network, or another suitable personal area network. That said, in other embodiments, the network  810  could be realized as a wireless ad hoc network, a wireless local area network (WLAN), or local area network (LAN). The client device  806  includes or is coupled to a display device, such as a monitor, screen, or another conventional electronic display, capable of graphically presenting data and/or information pertaining to the physiological condition of the patient. The client device  806  also includes or is otherwise associated with a user input device, such as a keyboard, a mouse, a touchscreen, or the like, capable of receiving input data and/or other information from the user of the client device  806 . 
     In exemplary embodiments, a user, such as the patient, the patient&#39;s doctor or another healthcare provider, or the like, manipulates the client device  806  to execute a client application  808  that supports communicating with the medical device  802  via the network  810 . In this regard, the client application  808  supports establishing a communications session with the medical device  802  on the network  810  and receiving data and/or information from the medical device  802  via the communications session. The medical device  802  may similarly execute or otherwise implement a corresponding application or process that supports establishing the communications session with the client application  808 . The client application  808  generally represents a software module or another feature that is generated or otherwise implemented by the client device  806  to support the processes described herein. Accordingly, the client device  806  generally includes a processing system and a data storage element (or memory) capable of storing programming instructions for execution by the processing system, that, when read and executed, cause processing system to create, generate, or otherwise facilitate the client application  808  and perform or otherwise support the processes, tasks, operations, and/or functions described herein. Depending on the embodiment, the processing system may be implemented using any suitable processing system and/or device, such as, for example, one or more processor devices, central processing units (CPUs), controllers, microprocessors, microcontrollers, processing cores and/or other hardware computing resources configured to support the operation of the processing system described herein. Similarly, the data storage element or memory may be realized as a random-access memory (RAM), read only memory (ROM), flash memory, magnetic or optical mass storage, or any other suitable non-transitory short or long-term data storage or other computer-readable media, and/or any suitable combination thereof. 
     In one or more embodiments, the client device  806  and the medical device  802  establish an association (or pairing) with one another over the network  810  to support subsequently establishing a point-to-point or peer-to-peer communications session between the medical device  802  and the client device  806  via the network  810 . For example, in accordance with some embodiments, the network  810  is realized as a Bluetooth network, wherein the medical device  802  and the client device  806  are paired with one another (e.g., by obtaining and storing network identification information for one another) by performing a discovery procedure or another suitable pairing procedure. The pairing information obtained during the discovery procedure allows either of the medical device  802  or the client device  806  to initiate the establishment of a secure communications session via the network  810 . 
     In one or more exemplary embodiments, the client application  808  is also configured to store or otherwise maintain an address and/or other identification information for the remote device  814  on the second network  812 . In this regard, the second network  812  may be physically and/or logically distinct from the network  810 , such as, for example, the Internet, a cellular network, a wide area network (WAN), or the like. The remote device  814  generally represents a server or other computing device configured to receive and analyze or otherwise monitor measurement data, event log data, and potentially other information obtained for the patient associated with the medical device  802 . In exemplary embodiments, the remote device  814  is coupled to a database  816  configured to store or otherwise maintain data associated with individual patients. In practice, the remote device  814  may reside at a location that is physically distinct and/or separate from the medical device  802  and the client device  806 , such as, for example, at a facility that is owned and/or operated by or otherwise affiliated with a manufacturer of the medical device  802 . For purposes of explanation, but without limitation, the remote device  814  may alternatively be referred to herein as a server. 
     Still referring to  FIG.  8   , the sensing element  804  generally represents the component of the patient monitoring system  800  that is configured to generate, produce, or otherwise output one or more electrical signals indicative of a physiological condition that is sensed, measured, or otherwise quantified by the sensing element  804 . In this regard, the physiological condition of a patient influences a characteristic of the electrical signal output by the sensing element  804 , such that the characteristic of the output signal corresponds to or is otherwise correlative to the physiological condition that the sensing element  804  is sensitive to. In exemplary embodiments, the sensing element  804  is realized as an interstitial glucose sensing element inserted at a location on the body of the patient that generates an output electrical signal having a current (or voltage) associated therewith that is correlative to the interstitial fluid glucose level that is sensed or otherwise measured in the body of the patient by the sensing element  804 . 
     The medical device  802  generally represents the component of the patient monitoring system  800  that is communicatively coupled to the output of the sensing element  804  to receive or otherwise obtain the measurement data samples from the sensing element  804  (e.g., the measured glucose and characteristic impedance values), store or otherwise maintain the measurement data samples, and upload or otherwise transmit the measurement data to the remote device  814  or server via the client device  806 . In one or more embodiments, the medical device  802  is realized as an infusion device  102 ,  200 ,  502  configured to deliver a fluid, such as insulin, to the body of the patient. That said, in other embodiments, the medical device  802  could be a standalone sensing or monitoring device separate and independent from an infusion device (e.g., sensing arrangement  104 ,  504 ). It should be noted that although  FIG.  8    depicts the medical device  802  and the sensing element  804  as separate components, in practice, the medical device  802  and the sensing element  804  may be integrated or otherwise combined to provide a unitary device that can be worn by the patient. 
     In exemplary embodiments, the medical device  802  includes a control module  822 , a data storage element  824  (or memory), and a communications interface  826 . The control module  822  generally represents the hardware, circuitry, logic, firmware and/or other component(s) of the medical device  802  that is coupled to the sensing element  804  to receive the electrical signals output by the sensing element  804  and perform or otherwise support various additional tasks, operations, functions and/or processes described herein. Depending on the embodiment, the control module  822  may be implemented or realized with a general purpose processor device, a microprocessor device, a controller, a microcontroller, a state machine, a content addressable memory, an application specific integrated circuit, a field programmable gate array, any suitable programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof, designed to perform the functions described herein. In some embodiments, the control module  822  includes an analog-to-digital converter (ADC) or another similar sampling arrangement that samples or otherwise converts an output electrical signal received from the sensing element  804  into corresponding digital measurement data value. In other embodiments, the sensing element  804  may incorporate an ADC and output a digital measurement value. 
     The communications interface  826  generally represents the hardware, circuitry, logic, firmware and/or other components of the medical device  802  that are coupled to the control module  822  for outputting data and/or information from/to the medical device  802  to/from the client device  806 . For example, the communications interface  826  may include or otherwise be coupled to one or more transceiver modules capable of supporting wireless communications between the medical device  802  and the client device  806 . In exemplary embodiments, the communications interface  826  is realized as a Bluetooth transceiver or adapter configured to support Bluetooth Low Energy (BLE) communications. 
     In exemplary embodiments, the remote device  814  receives, from the client device  806 , measurement data values associated with a particular patient (e.g., sensor glucose measurements, acceleration measurements, and the like) that were obtained using the sensing element  804 , and the remote device  814  stores or otherwise maintains the historical measurement data in the database  816  in association with the patient (e.g., using one or more unique patient identifiers). Additionally, the remote device  814  may also receive, from or via the client device  806 , meal data or other event log data that may be input or otherwise provided by the patient (e.g., via client application  808 ) and store or otherwise maintain historical meal data and other historical event or activity data associated with the patient in the database  816 . In this regard, the meal data include, for example, a time or timestamp associated with a particular meal event, a meal type or other information indicative of the content or nutritional characteristics of the meal, and an indication of the size associated with the meal. In exemplary embodiments, the remote device  814  also receives historical fluid delivery data corresponding to basal or bolus dosages of fluid delivered to the patient by an infusion device  102 ,  200 ,  502 . For example, the client application  808  may communicate with an infusion device  102 ,  200 ,  502  to obtain insulin delivery dosage amounts and corresponding timestamps from the infusion device  102 ,  200 ,  502 , and then upload the insulin delivery data to the remote device  814  for storage in association with the particular patient. The remote device  814  may also receive geolocation data and potentially other contextual data associated with a device  802 ,  806  from the client device  806  and/or client application  808 , and store or otherwise maintain the historical operational context data in association with the particular patient. In this regard, one or more of the devices  802 ,  806  may include a global positioning system (GPS) receiver or similar modules, components or circuitry capable of outputting or otherwise providing data characterizing the geographic location of the respective device  802 ,  806  in real-time. 
     The historical patient data may be analyzed by one or more of the remote device  814 , the client device  806 , and/or the medical device  802  to alter or adjust operation of an infusion device  102 ,  200 ,  502  to influence fluid delivery in a personalized manner. For example, the patient&#39;s historical meal data and corresponding measurement data or other contextual data may be analyzed to predict a future time when the next meal is likely to be consumed by the patient, the likelihood of a future meal event within a specific time period, the likely size or amount of carbohydrates associated with a future meal, the likely type or nutritional content of the future meal, and/or the like. Moreover, the patient&#39;s historical measurement data for postprandial periods following historical meal events may be analyzed to model or otherwise characterize the patient&#39;s glycemic response to the predicted size and type of meal for the current context (e.g., time of day, day of week, geolocation, etc.). One or more aspects of the infusion device  102 ,  200 ,  502  that control or regulate insulin delivery may then be modified or adjusted to proactively account for the patient&#39;s likely meal activity and glycemic response. 
     In one or more exemplary embodiments, the remote device  814  utilizes machine learning to determine which combination of historical sensor glucose measurement data, historical delivery data, historical auxiliary measurement data (e.g., historical acceleration measurement data, historical heart rate measurement data, and/or the like), historical event log data, historical geolocation data, and other historical or contextual data are correlated to or predictive of the occurrence of a particular event, activity, or metric for a particular patient, and then determines a corresponding equation, function, or model for calculating the value of the parameter of interest based on that set of input variables. Thus, the model is capable of characterizing or mapping a particular combination of one or more of the current (or recent) sensor glucose measurement data, auxiliary measurement data, delivery data, geographic location, patient behavior or activities, and the like to a value representative of the current probability or likelihood of a particular event or activity or a current value for a parameter of interest. It should be noted that since each patient&#39;s physiological response may vary from the rest of the population, the subset of input variables that are predictive of or correlative for a particular patient may vary from other patients. Additionally, the relative weightings applied to the respective variables of that predictive subset may also vary from other patients who may have common predictive subsets, based on differing correlations between a particular input variable and the historical data for that particular patient. It should be noted that any number of different machine learning techniques may be utilized by the remote device  814  to determine what input variables are predictive for a current patient of interest, such as, for example, artificial neural networks, genetic programming, support vector machines, Bayesian networks, probabilistic machine learning models, or other Bayesian techniques, fuzzy logic, heuristically derived combinations, or the like. 
     The insulin infusion device may incorporate or leverage the control algorithms, processing schemes, and operating methodologies (or suitably modified, updated, or customized versions thereof) of the type described in U.S. Pat. No. 9,526,834 and International (PCT) patent publication number WO 2014/035570; the content of these published documents is incorporated herein by reference. 
     Each of the devices or components that are described above with reference to  FIGS.  1 - 8    can be realized as a computer-based or processor-based component. As such, an exemplary embodiment of a computer-based or processor-based device  900  will be described with reference to  FIG.  9   , which is a simplified block diagram representation of an exemplary embodiment of the computer-based or processor-based device  900  that is suitable for deployment in the systems shown in  FIGS.  1 - 8   . In addition, the computer-based or processor-based device  900  that will be described with reference to  FIG.  9    can also be used to implement a system  1000  that includes an estimation model  1040  for estimating glucose values, as will be described below with reference to  FIGS.  10 - 12   . 
     The illustrated embodiment of the device  900  is intended to be a high-level and generic representation of one suitable platform. In this regard, any of the computer-based or processor-based components of the system  100  can utilize the architecture of the device  900 . The illustrated embodiment of the device  900  generally includes, without limitation: at least one processor  902 ; a suitable amount of memory  904 ; device-specific hardware, software, firmware, and/or features  906 ; a user interface  908 ; a communication module  910 ; and a display element  912 . Of course, an implementation of the device  900  may include additional elements, components, modules, and functionality configured to support various features that are unrelated to the subject matter described here. For example, the device  900  may include certain features and elements to support conventional functions that might be related to the particular implementation and deployment of the device  900 . In practice, the elements of the device  900  may be coupled together via a bus or any suitable interconnection architecture  914 . 
     The processor  902  may be implemented or performed with a general purpose processor, a content addressable memory, a digital signal processor, an application specific integrated circuit, a field programmable gate array, any suitable programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination designed to perform the functions described here. Moreover, the processor  902  may be implemented as a combination of computing devices, e.g., a combination of a digital signal processor and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a digital signal processor core, or any other such configuration. 
     The memory  904  may be realized as RAM memory, flash memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. In this regard, the memory  904  can be coupled to the processor  902  such that the processor  902  can read information from, and write information to, the memory  904 . In the alternative, the memory  904  may be integral to the processor  902 . As an example, the processor  902  and the memory  904  may reside in an ASIC. At least a portion of the memory  904  can be realized as a computer storage medium, e.g., a tangible computer-readable medium having computer-executable instructions stored thereon. The computer-executable instructions, when read and executed by the processor  902 , cause the device  900  to perform certain tasks, operations, functions, and processes that are specific to the particular embodiment. In this regard, the memory  904  may represent one suitable implementation of such computer-readable media. Alternatively, or additionally, the device  900  could receive and cooperate with computer-readable media (not separately shown) that is realized as a portable or mobile component or platform, e.g., a portable hard drive, a USB flash drive, an optical disc, or the like. 
     The device-specific hardware, software, firmware, and features  906  may vary from some embodiments of the device  900  to another. For example, the device-specific hardware, software, firmware, and features  906  will support: smartphone functions and features when the device  900  is realized as a mobile telephone; conventional personal computer functions and features if the device  900  is realized as a laptop or tablet computer; insulin pump operations when the device  900  is realized as an insulin infusion device; etc. In practice, certain portions or aspects of the device-specific hardware, software, firmware, and features  906  may be implemented in one or more of the other blocks depicted in  FIG.  9   . 
     The user interface  908  may include or cooperate with various features to allow a user to interact with the device  900 . Accordingly, the user interface  908  may include various human-to-machine interfaces, e.g., a keypad, keys, a keyboard, buttons, switches, knobs, a touchpad, a joystick, a pointing device, a virtual writing tablet, a touch screen, a microphone, or any device, component, or function that enables the user to select options, input information, or otherwise control the operation of the device  900 . The user interface  908  may include one or more graphical user interface (GUI) control elements that enable a user to manipulate or otherwise interact with an application via the display element  912 . 
     The communication module  910  facilitates data communication between the device  900  and other components as needed during the operation of the device  900 . In the context of this description, the communication module  910  can be employed to transmit or stream device-related control data, patient-related data, device-related status or operational data, glycemic insight messages and notifications, and the like. It should be appreciated that the particular configuration and functionality of the communication module  910  can vary depending on the hardware platform and specific implementation of the device  900 . In practice, an embodiment of the device  900  may support wireless data communication and/or wired data communication, using various data communication protocols. For example, the communication module  910  could support one or more wireless data communication protocols, techniques, or methodologies, including, without limitation: RF; IrDA (infrared); Bluetooth; ZigBee (and other variants of the IEEE 802.15 protocol); IEEE 802.11 (any variation); IEEE 802.16 (WiMAX or any other variation); Direct Sequence Spread Spectrum; Frequency Hopping Spread Spectrum; cellular/wireless/cordless telecommunication protocols; wireless home network communication protocols; paging network protocols; magnetic induction; satellite data communication protocols; wireless hospital or health care facility network protocols such as those operating in the WMTS bands; GPRS; and proprietary wireless data communication protocols such as variants of Wireless USB. Moreover, the communication module  910  could support one or more wired/cabled data communication protocols, including, without limitation: Ethernet; powerline; home network communication protocols; USB; IEEE 1394 (Firewire); hospital network communication protocols; and proprietary data communication protocols. 
     The display element  912  is suitably configured to enable the device  900  to render and display various screens, insight messages, notifications, GUIs, GUI control elements, drop down menus, auto-fill fields, text entry fields, message fields, or the like. Of course, the display element  912  may also be utilized for the display of other information during the operation of the device  900 , as is well understood. Notably, the specific configuration, operating characteristics, size, resolution, and functionality of the display element  910  can vary depending upon the practical implementation of the device  900 . For example, if the device  900  is a laptop computer, then the display element  912  may be a relatively large monitor. Alternatively, if the device  900  is a cellular telephone device, then the display element  912  may be a relatively small integrated display screen, such as a touch-sensitive screen. 
       FIG.  10    is a block diagram of a system  1000  for estimating glucose values for a particular user or patient in accordance with the disclosed embodiments. The system  1000  includes an estimation model  1040  that is configured to receive various inputs  1010 ,  1020 ,  1030 . The estimation model  1040  can be executed at a processing system. The processing system can be implemented at any of the devices described herein including those illustrated and described above with reference to  FIGS.  1  and  8   , and more generically at a computer-based or processor-based device  900  such as that illustrated and described above with reference to  FIG.  9   . For instance, the processing system can be implemented at a backend server system, such as, the remote device  814  of  FIG.  8   , at a client device  806  of  FIG.  8    (e.g., patient&#39;s smartphone), at a medical device  802  of  FIG.  8    (e.g., an insulin infusion device  502  of  FIG.  5   ) or other end device, such as the auxiliary sensing arrangement(s)  506  (or activity tracker device, ring, necklace, vest, etc.) and the blood glucose meter  530  of  FIG.  5   . Thus, in some embodiments, the processing system can be implemented at a backend server system, such as, the remote device  814  of  FIG.  8   . For example, the estimation model can be executed or run as part of a web application at the backend server system, and the backend server system can then communicate the estimated glucose values to a client device (e.g., patient&#39;s smartphone), an insulin infusion device or other end device. In another embodiment, the processing system can be implemented at a client device and the estimation model can be executed as part of a mobile application at the client device. In another embodiment, the processing system can be implemented at an insulin infusion device and the estimation model can be executed as part of an application at the insulin infusion device. 
     In one nonlimiting embodiment, the inputs include discrete glucose measurements  1010  from a blood glucose meter (BGM), contextual activity data  1020  from an activity tracker or equivalent source of activity data such as a smartphone or other health related device, and optionally contextual data  1030  from other sources. The contextual activity data  1020  collected from the activity tracker or equivalent source of activity data (e.g., smartphone or other health related device) can include, for example, one or more of: metabolic data about the patient (e.g., calories burned); physical activity data about the user (e.g., heart rate data for the patient, exercise data for the patient, activity type, duration and intensity data, data about a number of steps taken by the patient during a time period, metabolic equivalents and other parameters); data from a fitness or exercise advisor device or application that provides fitness/exercise suggestions or recommendations to users; and other raw contextual data such as accelerometer (x,y,z) data, geolocation data, iBeacon location data, skin temperature data, ambient air temperature data, bioimpedance heart rate data, sweat data (e.g., GSR-conductance), blood pressure data, shake detection data, pedometer data, barometer data, gyroscope data, meal log data, orientation (azimuth, pitch, roll (degrees)) data; health kit data (such as data from Apple® Healthkit, Google® Fit, etc.), medication/prescription information data, user gestures data, uv light detector data, magnetometer data, respiration data, muscle activity data, pulse oximeter data, blood+interstitial fluid pH data, metabolic equivalents (METS) data, sleep quality/time data, EMR and lab data, etc. The contextual data  1030  from other sources can include, for example, historical sensor glucose measurement data, historical delivery data, historical auxiliary measurement data such as historical acceleration measurement data, historical heart rate measurement data, skin conductance, and/or the like, historical event log data, historical geolocation data, and other historical or contextual data are correlated to or predictive of the occurrence of a particular event, activity, or metric for a particular patient. The estimation model  1040  processes at least some of the various inputs to continuously generate estimated glucose values  1080 . 
     In one or more exemplary embodiments, the remote device  814  of  FIG.  8    utilizes machine learning to determine, based on discrete glucose measurements  1010  from a blood glucose meter (e.g. the blood glucose meter  530  of  FIG.  5   ), contextual activity data  1020  from as the auxiliary sensing arrangement(s)  506  (e.g., from “activity tracker” or equivalent source of activity data), and optionally contextual data  1030  from other sources, to generate continuous estimated glucose values  1080 . Depending on the implementation, the machine learning model  1060  can be a corresponding equation, function, or model for calculating the estimated glucose values  1080  based on the set of input variables. Thus, the machine learning model  1060  is capable of characterizing or mapping a particular combination of inputs to a value representative of the estimated glucose values  1080 . 
     Artificial intelligence is an area of computer science emphasizes the creation of intelligent machines that work and react like humans. Some of the activities computers with artificial intelligence are designed for include learning. Examples of artificial intelligence algorithms include, but are not limited to, key learning, actor critic methods, reinforce, deep deterministic policy gradient (DDPG), multi-agent deep deterministic policy gradient (MADDPG), etc. Machine learning refers to an artificial intelligence discipline geared toward the technological development of human knowledge. 
     Machine learning facilitates a continuous advancement of computing through exposure to new scenarios, testing and adaptation, while employing pattern and trend detection for improved decisions and subsequent, though not identical, situations. Machine learning (ML) algorithms and statistical models can be used by computer systems to effectively perform a specific task without using explicit instructions, relying on patterns and inference instead. Machine learning algorithms build a mathematical model based on sample data, known as “training data,” in order to make predictions or decisions without being explicitly programmed to perform the task. Machine learning algorithms can be used when it is infeasible to develop an algorithm of specific instructions for performing the task. 
     For example, supervised learning algorithms build a mathematical model of a set of data that contains both the inputs and the desired outputs. The data is known as training data and consists of a set of training examples. Each training example has one or more inputs and a desired output, also known as a supervisory signal. In the case of semi-supervised learning algorithms, some of the training examples are missing the desired output. In the mathematical model, each training example is represented by an array or vector, and the training data by a matrix. Through iterative optimization of an objective function, supervised learning algorithms learn a function that can be used to predict the output associated with new inputs. An optimal function will allow the algorithm to correctly determine the output for inputs that were not a part of the training data. An algorithm that improves the accuracy of its outputs or predictions over time is said to have learned to perform that task. Supervised learning algorithms include classification and regression. Classification algorithms are used when the outputs are restricted to a limited set of values, and regression algorithms are used when the outputs may have any numerical value within a range. Similarity learning is an area of supervised machine learning closely related to regression and classification, but the goal is to learn from examples using a similarity function that measures how similar or related two objects are. 
     Reinforcement learning is an area of machine learning concerned with how software agents ought to take actions in an environment so as to maximize some notion of cumulative reward. Due to its generality, the field is studied in many other disciplines, such as game theory, control theory, operations research, information theory, simulation-based optimization, multi-agent systems, swarm intelligence, statistics and genetic algorithms. In machine learning, the environment is typically represented as a Markov Decision Process (MDP). Many reinforcement learning algorithms use dynamic programming techniques. Reinforcement learning algorithms do not assume knowledge of an exact mathematical model of the MDP and are used when exact models are infeasible. 
     In accordance with one non-limiting implementation, the estimation model  1040  can be an ensemble model  1050 . An ensemble model  1050  includes two or more related, but different analytical models that are run or executed at the same time, where the results generated by each can then be synthesized into a single score or spread in order to improve the accuracy of predictive analytics. To explain further, in predictive modeling and other types of data analytics, a single model based on one data sample can have biases, high variability or outright inaccuracies that can affect the reliability of its analytical findings. By combining different models or analyzing multiple samples, the effects of those limitations can be reduced to provide better information. As such, ensemble methods can use multiple machine learning algorithms to obtain better predictive performance than could be obtained from any of the constituent learning algorithms alone. 
     An ensemble is a supervised learning algorithm because it can be trained and then used to make predictions. The trained ensemble, therefore, represents a single hypothesis that is not necessarily contained within the hypothesis space of the models from which it is built. Thus, ensembles can be shown to have more flexibility in the functions they can represent. An ensemble model can include a set of individually trained classifiers (such as neural networks or decision trees) whose predictions are combined. 
     For instance, one common example of ensemble modeling is a random forest model which is a type of analytical model that leverages multiple decision trees and is designed to predict outcomes based on different variables and rules. A random forest model blends decision trees that may analyze different sample data, evaluate different factors or weight common variables differently. The results of the various decision trees are then either converted into a simple average or aggregated through further weighting. The emergence of Hadoop and other big data technologies has allowed greater volumes of data to be stored and analyzed, which can allow analytical models to be run on different data samples. 
     In some embodiments, the ensemble model  1050  can include or be built using at least one machine learning model  1060  and a physiological model  1070 . The physiological model  1070  can be, for example, a population-based model of one or more equations (e.g., a set of differential equations) that are generally applicable to any patient, but has different variables or parameters that are weighted in accordance with a particular patient&#39;s individual parameters to mimic the physiology of that patient. In other words, because each patient&#39;s physiological response may vary from the rest of the population, the relative weightings applied to the respective variables of the physiological model  1070  may also vary from other patients. The physiological model  1070  can be used in conjunction with the machine learning model(s)  1060  to help confine estimations or predictions within a realistic range. 
     Depending on the implementation, any number of machine learning models can be combined to optimize the ensemble model  1050 . Examples of machine learning algorithms or models that can be implemented at the machine learning model  1060  can include, but are not limited to: regression models such as linear regression, logistic regression, and K-means clustering; one or more decision tree models (e.g., a random forest model); one or more support vector machines; one or more artificial neural networks; one or more deep learning networks (e.g., at least one recurrent neural network, sequence to sequence mapping using deep learning, sequence encoding using deep learning, etc.); fuzzy logic based models; genetic programming models; Bayesian networks or other Bayesian techniques, probabilistic machine learning models; Gaussian processing models; Hidden Markov models; time series methods such as Autoregressive Moving Average (ARMA) models, Autoregressive Integrated Moving Average (ARIMA) models, Autoregressive conditional heteroskedasticity (ARCH) models; generalized autoregressive conditional heteroskedasticity (GARCH) models; moving-average (MA) models or other models; and heuristically derived combinations of any of the above, etc. The types of machine learning algorithms differ in their approach, the type of data they input and output, and the type of task or problem that they are intended to solve. 
     A Hidden Markov model (HMM) is a statistical Markov model in which the system being modeled is assumed to be a Markov process with unobserved (hidden) states. An HMM can be considered as the simplest dynamic Bayesian network. A Bayesian network, belief network or directed acyclic graphical model is a probabilistic graphical model that represents a set of random variables and their conditional independence with a directed acyclic graph (DAG). Bayesian networks that model sequences of variables are called dynamic Bayesian networks. Generalizations of Bayesian networks that can represent and solve decision problems under uncertainty are called influence diagrams. 
     Support vector machines (SVMs), also known as support vector networks, are a set of related supervised learning methods used for classification and regression. Given a set of training examples, each marked as belonging to one of two categories, an SVM training algorithm builds a model that predicts whether a new example falls into one category or the other. An SVM training algorithm is a non-probabilistic, binary, linear classifier. In addition to performing linear classification, SVMs can efficiently perform a non-linear classification using what is called the kernel trick, implicitly mapping their inputs into high-dimensional feature spaces. 
     Decision tree learning uses a decision tree as a predictive model to go from observations about an item (represented in the branches) to conclusions about the item&#39;s target value (represented in the leaves). Tree models where the target variable can take a discrete set of values are called classification trees; in these tree structures, leaves represent class labels and branches represent conjunctions of features that lead to those class labels. Decision trees where the target variable can take continuous values (typically real numbers) are called regression trees. In decision analysis, a decision tree can be used to visually and explicitly represent decisions and decision making. 
     Deep learning algorithms can refer to a collection of algorithms used in machine learning, that are used to model high-level abstractions and data through the use of model architectures, which are composed of multiple nonlinear transformations. Deep learning is a specific approach used for building and training neural networks. Deep learning consists of multiple hidden layers in an artificial neural network. Examples of deep learning algorithms can include, for example, Siamese networks, transfer learning, recurrent neural networks (RNNs), long short term memory (LSTM) networks, convolutional neural networks (CNNs), transformers, etc. For instance, deep learning approaches can make use of autoregressive Recurrent Neural Networks (RNN), such as the long short-term memory (LSTM) and the Gated Recurrent Unit (GRU). One neural network architecture for time series forecasting using RNNs (and variants) is an autoregressive seq2seq neural network architecture, which acts as an autoencoder. 
     In some embodiments, the ensemble model  1050  can include one or more deep learning algorithms. It should be noted that any number of different machine learning techniques may also be utilized. Depending on the implementation, the ensemble model  1050  can be implemented as a bootstrap aggregating ensemble algorithm (also referred to as a bagging classifier method), as a boosting ensemble algorithm or classifier algorithm, as a stacking ensemble algorithm or classifier algorithm, as bucket of models ensemble algorithms, as Bayes optimal classifier algorithms, as Bayesian parameter averaging algorithms, as Bayesian model combination algorithms, etc. 
     Bootstrap aggregating, often abbreviated as bagging, involves having each model in the ensemble vote with equal weight. In order to promote model variance, bagging trains each model in the ensemble using a randomly drawn subset of the training set. As an example, the random forest algorithm combines random decision trees with bagging to achieve very high classification accuracy. A bagging classifier or ensemble method creates individuals for its ensemble by training each classifier on a random redistribution of the training set. Each classifier&#39;s training set can be generated by randomly drawing, with replacement, N examples—where N is the size of the original training set; many of the original examples may be repeated in the resulting training set while others may be left out. Each individual classifier in the ensemble is generated with a different random sampling of the training set. Bagging is effective on “unstable” learning algorithms (e.g., neural networks and decision trees), where small changes in the training set result in large changes in predictions. 
     By contrast, boosting involves incrementally building an ensemble by training each new model instance to emphasize the training instances that previous models mis-classified. In some cases, boosting has been shown to yield better accuracy than bagging, but it also tends to be more likely to over-fit the training data. A boosting classifier can refer to a family of methods that can be used to produce a series of classifiers. The training set used for each member of the series is chosen based on the performance of the earlier classifier(s) in the series. In boosting, examples that are incorrectly predicted by previous classifiers in the series are chosen more often than examples that were correctly predicted. Thus, boosting attempts to produce new classifiers that are better able to predict examples for which the current ensemble&#39;s performance is poor. A common implementation of boosting is Adaboost, although some newer algorithms are reported to achieve better results. 
     Stacking (sometimes called stacked generalization) involves training a learning algorithm to combine the predictions of several other learning algorithms. Stacking works in two phases: multiple base classifiers are used to predict the class, and then a new learner is used to combine their predictions with the aim of reducing the generalization error. First, all of the other algorithms are trained using the available data, then a combiner algorithm is trained to make a final prediction using all the predictions of the other algorithms as additional inputs. If an arbitrary combiner algorithm is used, then stacking can theoretically represent any of the ensemble techniques described in this article, although, in practice, a logistic regression model is often used as the combiner. 
     A “bucket of models” is an ensemble technique in which a model selection algorithm is used to choose the best model for each problem. When tested with only one problem, a bucket of models can produce no better results than the best model in the set, but when evaluated across many problems, it will typically produce much better results, on average, than any model in the set. One common approach used for model-selection is cross-validation selection (sometimes called a “bake-off contest”). Cross-validation selection can be summed up as try them all with the training set and pick the one that works best. Gating is a generalization of Cross-Validation Selection. It involves training another learning model to decide which of the models in the bucket is best-suited to solve the problem. Often, a perceptron is used for the gating model. It can be used to pick the “best” model, or it can be used to give a linear weight to the predictions from each model in the bucket. When a bucket of models is used with a large set of problems, it may be desirable to avoid training some of the models that take a long time to train. Landmark learning is a meta-learning approach that seeks to solve this problem. It involves training only the fast (but imprecise) algorithms in the bucket, and then using the performance of these algorithms to help determine which slow (but accurate) algorithm is most likely to do best. 
     The Bayes optimal classifier is a classification technique. It is an ensemble of all the hypotheses in the hypothesis space. On average, no other ensemble can outperform it. The naive Bayes optimal classifier is a version of this that assumes that the data is conditionally independent on the class and makes the computation more feasible. Each hypothesis is given a vote proportional to the likelihood that the training dataset would be sampled from a system if that hypothesis were true. To facilitate training data of finite size, the vote of each hypothesis is also multiplied by the prior probability of that hypothesis. The hypothesis represented by the Bayes optimal classifier, however, is the optimal hypothesis in ensemble space (the space of all possible ensembles. 
     Bayesian parameter averaging (BPA) is an ensemble technique that seeks to approximate the Bayes optimal classifier by sampling hypotheses from the hypothesis space and combining them using Bayes&#39; law. Unlike the Bayes optimal classifier, Bayesian model averaging (BMA) can be practically implemented. Hypotheses are typically sampled using a Monte Carlo sampling technique such as MCMC. For example, Gibbs sampling may be used to draw hypotheses that are representative of a distribution. It has been shown that under certain circumstances, when hypotheses are drawn in this manner and averaged according to Bayes&#39; law, this technique has an expected error that is bounded to be at most twice the expected error of the Bayes optimal classifier. 
     Bayesian model combination (BMC) is an algorithmic correction to Bayesian model averaging (BMA). Instead of sampling each model in the ensemble individually, it samples from the space of possible ensembles (with model weightings drawn randomly from a Dirichlet distribution having uniform parameters). This modification overcomes the tendency of BMA to converge toward giving all of the weight to a single model. Although BMC is somewhat more computationally expensive than BMA, it tends to yield dramatically better results. The results from BMC have been shown to be better on average (with statistical significance) than BMA, and bagging. The use of Bayes&#39; law to compute model weights necessitates computing the probability of the data given each model. Typically, none of the models in the ensemble are exactly the distribution from which the training data were generated, so all of them correctly receive a value close to zero for this term. This would work well if the ensemble were big enough to sample the entire model-space, but such is rarely possible. Consequently, each pattern in the training data will cause the ensemble weight to shift toward the model in the ensemble that is closest to the distribution of the training data. It essentially reduces to an unnecessarily complex method for doing model selection. The possible weightings for an ensemble can be visualized as lying on a simplex. At each vertex of the simplex, all of the weight is given to a single model in the ensemble. BMA converges toward the vertex that is closest to the distribution of the training data. By contrast, BMC converges toward the point where this distribution projects onto the simplex. In other words, instead of selecting the one model that is closest to the generating distribution, it seeks the combination of models that is closest to the generating distribution. The results from BMA can often be approximated by using cross-validation to select the best model from a bucket of models. Likewise, the results from BMC may be approximated by using cross-validation to select the best ensemble combination from a random sampling of possible weightings. 
       FIG.  11    is a flowchart that illustrates a method  1100  for generating an estimation model for a particular patient in accordance with the disclosed embodiments. The method  1100  begins at  1110  where a computing system trains multiple generic estimation models. Each generic estimation model can be modeled for a particular group of users. At  1120 , the computing system tests the generic estimation models, and then at  1130 , the computing system validates the generic estimation models. For example, in some embodiments, the computing system can train multiple population-base models for type 1 and type 2 patients using different combinations of demographic parameters such as age, gender, location and diabetes history such as diabetes onset, years on insulin, therapy type using existing BG, insulin, meal information, activity data from an activity tracker, and CGM data to train, test and validate the models. 
     Once all the generic estimation models have been validated, the method  1100  proceeds to  1140 , where the computing system determines, based on characteristics of a particular user or patient, an applicable generic estimation model that is the best fit for that particular patient based on characteristics of that particular patient. The particular generic estimation model that is applicable for a particular patient varies based on the characteristics of that particular patient. 
     At  1150 , the computing system can then update the particular generic estimation model that was deployed at  1140  based on data that was collected for that particular patient to generate an estimation model for that particular patient. In other words, parameters of the generic estimation model that was selected and deployed  1140  can be updated and fine-tuned at  150  based on data that was collected for the particular patient in order to customize that generic estimation model such that it becomes an estimation model for that particular patient. 
     After the estimation model for that particular patient has been generated at  1150  it can be executed and updated any time new data is received for that patient. For example, in some embodiments, the new data can come from the blood glucose meter data (e.g., new blood glucose measurements), new contextual activity data that is received for that patient from the activity tracker, and/or new contextual data that is received for that patient from other sources. In one implementation, the estimation model for that particular patient can be updated each time there is a new data from the BGM. In another embodiment, the new data can be from a continuous glucose monitor. For instance, the CGM can be used periodically to collect CGM data for the particular patient for a certain period of time (e.g., for two weeks), and this newly collected CGM data can then be used to assess performance of the estimation model and/or update or re-train the estimation model for that particular patient. In addition, the CGM data can also be used to train and update the generic estimation models that were described above with reference to step  1110 . Furthermore, in some implementations, the CGM data can also be used at  1140  to select and deploy a different one of the generic estimation models for the particular patient. 
     As such, at  1160 , the computing system regularly determines whether new data is received, and if so, the method proceeds to  1170  where the estimation model for that particular patient is updated based on the new data to generate an updated estimation model that can be executed at a processing system (as will be described below). 
     After the estimation model for that particular patient is updated based on the new data at  1170 , the method loops to  1160 . As the estimation model for the particular patient is updated it becomes more fine-tuned and can be used to generate better estimated glucose values for the patient. In any point the estimation model can be used to estimate glucose values for the patient. One non-limiting embodiment will now be described with respect to  FIG.  12    where an estimation model is used to estimate glucose values for a patient. 
       FIG.  12    is a flowchart of a method  1200  in accordance with the disclosed embodiments. At  1210 , a processing system can receive intermittent glucose measurements from a blood glucose meter. At  1220  the processing system can also receive contextual activity data from an activity tracker. At  1230 , the processing system can also optionally receive other contextual data from other sources that are described above. In some embodiments, a first set of inputs comprising a sequence of intermittent blood glucose measurements are received from the calibrated blood glucose meter, and a second set of user inputs comprising contextual activity data collected from the user by an activity tracker are received from the activity tracker. Optionally, the other contextual data from other sources can include, for example, a third set of inputs from an insulin infusion device comprising insulin dispensed by the insulin infusion device and/or a fourth set of inputs comprising user entries that describe meal information. 
     At  1240 , a processing system can execute the machine learning-based estimation model for that patient to process the various inputs from steps  1210 ,  1220 ,  1230  to generate a sequence or set of estimated glucose values for that particular patient. The estimated glucose values are analogous to glucose measurements that can be taken by a glucose sensor in that the estimated glucose values estimate continuous glucose sensor measurement values. However, the processing system can generate the set of estimated glucose values without using information from a continuous glucose sensor arrangement. This can eliminate the need for a continuous glucose sensor, which can be a relatively expensive component with respect to a blood glucose meter, and thus saves patients a significant cost. It may also support intermittent CGM users that take “sensor vacations” due to various reasons which may include access, discomfort, seasonal needs, etc. In some embodiments, only the first set of inputs and the second set of user inputs are processed via the estimation model to generate the set of estimated glucose values. As used herein, “estimated glucose value,” and “estimated glucose concentration,” and the like may refer to a glucose level that has been estimated via the machine learning-based estimation model. In some embodiments, the estimated glucose values estimate and track interstitial or sensor glucose values (e.g., that are generated by a sensing arrangement such as a CGM device that has been calibrated using measured blood glucose values measured by a blood glucose meter). 
     Steps  1250 - 1280  are optional and relate to when and how the estimated glucose values can be used within the context of an insulin management system for diabetes management. For example, in one implementation, at  1250 , the computing system can monitor the set or sequence of estimated glucose values (e.g., discrete estimates of blood glucose levels) to determine if the sequence of the estimated glucose values are within an acceptable accuracy range that allows them to be used by an insulin management system. How the computing system can determine if the sequence of the estimated glucose values are within an acceptable accuracy range can vary depending on the implementation. For example, in some embodiments, the computing system can determine if the sequence of the estimated glucose values are within an acceptable accuracy range by measuring a difference between estimated glucose value and intermittent glucose measurements from a blood glucose meter (or equivalent device) and then comparing that difference to an accuracy threshold. In another embodiment, the computing system can determine if the sequence of the estimated glucose values are within an acceptable accuracy range by measuring difference between estimated glucose value and periodic measurements that were taken by a CGM device and then comparing that difference to an accuracy threshold. 
     When the estimated glucose values are determined (at  1250 ) to not be within an acceptable accuracy range that allows them to be used by an insulin management system, the method  1200  proceeds to  1260 , where a notification or an alert can be generated that can be perceptible to the patient or another user who is monitoring the patient. For example, in some embodiments, when the estimated glucose values are not in acceptable accuracy ranges, a notification or alert can be generated to inform the user that they should not trust the estimated glucose values being generated by the estimation model and to recommend that the user to wear another sensor (e.g., CGM) to retrain the estimation model. Any number of alerting methodologies can be employed at step  1260 , including, but not limited to, presenting (via a display device) graphical elements and text associated with notifications and alerts for the glucose control system (see reference  100 ,  FIG.  1   ). In some embodiments, notifications and alerts can be presented by an insulin pump device associated with a computing device and/or presented via a communicatively coupled personal computing device (e.g., a laptop computer, a tablet computer, a smartphone). Such notifications and alerts may include, without limitation: audio alerts (e.g., sound effects, articulated speech alerts, alarms), visual alerts (e.g., graphical elements and text presented via user interface or display of the insulin delivery pump, text effects, flashing or otherwise activated lights, color changes), text alerts (e.g., a text-based message transmitted via Short Message Service (SMS), an email message transmitted via the internet), and/or any other type of alert generated to attract the attention of the user. In addition, in some embodiments, when it is determined (at  1250 ) that the estimated glucose values are not within an acceptable accuracy range (that allows them to be used by an insulin management system), one or more displays may be controlled so that the estimated glucose values are not presented to the user. Following  1260 , the method  1200  can then end at  1270 . 
     When the estimated glucose values are determined (at  1250 ) to be within an acceptable accuracy range that allows them to be used by an insulin management system, the method  1200  proceeds to  1280 , where the estimated glucose values can be utilized the insulin delivery system, and estimates can continue to be generated in near real-time. The actions that can be taken at the insulin delivery system based on the estimated glucose values vary depending on the implementation. For example, actions that can be taken at the insulin delivery system based on the estimated glucose values can include controlling an insulin infusion device based on the estimated glucose values so that it administers insulin to a patient, or generating a notification or an alert, based on the estimated glucose values, that can be perceptible to the patient or another user who is monitoring the patient. As will be described below, the corrective actions and the notifications or alerts that can be generated vary depending on the implementation. 
     For example, in one implementation of step  1280 , the computing system operates cooperatively with an insulin delivery system and the machine learning-based estimation model to monitor estimated glucose levels of a patient, and to identify abnormalities in the estimated glucose levels. For example, the computing system can monitor the set or sequence of estimated glucose values (e.g., discrete estimates of blood glucose levels) to determine if the sequence of the estimated glucose values are within a low range, a high range, or an acceptable range. For instance, hypoglycemia is a deficiency of glucose in the bloodstream of the patient or user of the insulin delivery pump. Hypoglycemia may be generally associated with glucose values below 70 milligrams per deciliter (mg/dL), depending on certain patient-specific factors. Hyperglycemia is an excess of glucose in the bloodstream of the patient or user of the insulin delivery pump and may be generally associated with glucose values above 180 mg/dL, depending on certain patient-specific factors. Normal, healthy blood glucose levels, over every 24-hour cycle, generally range between 70 and 160 mg/dL. An abnormality in a sequence of blood glucose levels may include blood glucose levels below a predefined hypoglycemia threshold, blood glucose levels above a predefined hyperglycemia threshold, a decreasing blood glucose trend approaching or below a predefined hypoglycemia threshold, an increasing blood glucose trend approaching or above a predefined hyperglycemia threshold, or the like. 
     The abnormality indicates that a corrective action is required to maintain blood glucose stability at appropriate levels. Abnormalities in blood glucose levels require intervention to bring the patient&#39;s blood glucose levels into a safe and healthy range. As such, when the estimated glucose values are not within an acceptable range, the method  1200  can proceed to  1280 , where a corrective action can be taken at the insulin infusion device to deliver the patient an amount of insulin required to adequately treat the blood glucose abnormality to bring the blood glucose levels of the patient within normal limits and/or regulate their blood sugar levels. For example, in some embodiments, the estimated glucose values can be used to control and drive an insulin infusion device so that it administers insulin to a patient. 
     Exemplary embodiments of corrective actions are disclosed in, for example, in U.S. patent application Ser. No. 16/129,552, filed Sep. 12, 2018, entitled “SYSTEMS AND METHODS FOR ALERTING A USER TO DETECTED EFFECTS OF A RECENT THERAPY ADJUSTMENT,” and assigned to the assignee of the present invention, which is incorporated herein by reference in its entirety. Any number of corrective actions or intervention methodologies can be employed at step  1280 , such as, administration of a bolus of insulin (to decrease blood glucose levels) or administration of a quantity of carbohydrates, glucose, or other medication (to increase blood glucose levels). In other words, the corrective action may include the administration of a bolus of insulin (to decrease hyperglycemic blood glucose levels) or the administration of a dose of carbohydrates (to increase hypoglycemic blood glucose levels). 
     In addition, in some embodiments, at step  1280 , the computing system operates cooperatively with an insulin delivery system (e.g., insulin pump or manual insulin injection device such as an insulin pen) and the machine learning-based estimation model to monitor estimated glucose levels of a patient, and to generate a notification or an alert, based on the estimated glucose values, that can be perceptible to the patient or another user who is monitoring the patient (e.g., to inform the patient or the user of any abnormalities that are detected when the estimated glucose values are within the low range that is too low or within the high range that is too high). For instance, a notification or alert can be sent to the user to alert them that estimated glucose values are abnormal and help drive decision support for medication administration. Exemplary embodiments of alerts are disclosed, for example, in U.S. patent application Ser. No. 16/129,552, filed Sep. 12, 2018, entitled “SYSTEMS AND METHODS FOR ALERTING A USER TO DETECTED EFFECTS OF A RECENT THERAPY ADJUSTMENT,” and assigned to the assignee of the present invention, which is incorporated herein by reference in its entirety. Any number of alerting methodologies can be employed at step  1280 , including, but not limited to, presenting (via a display device) graphical elements and text associated with notifications and alerts for the glucose control system (see reference  100 ,  FIG.  1   ). In some embodiments, notifications and alerts can be presented by an insulin pump device associated with a computing device and/or presented via a communicatively coupled personal computing device (e.g., a laptop computer, a tablet computer, a smartphone). Such notifications and alerts may include, without limitation: audio alerts (e.g., sound effects, articulated speech alerts, alarms), visual alerts (e.g., graphical elements and text presented via user interface or display of the insulin delivery pump, text effects, flashing or otherwise activated lights, color changes), text alerts (e.g., a text-based message transmitted via Short Message Service (SMS), an email message transmitted via the internet), and/or any other type of alert generated to attract the attention of the user. 
     For example, a presentation module can identify appropriate graphical elements for presentation via a display device that identify a current estimated blood glucose level (e.g., various icons, text, and/or graphical elements associated with estimated blood glucose levels of a patient), a detected indication of a change of direction in the sequence of blood glucose levels, timing data associated with a detected indication of a change of direction in the sequence of blood glucose levels, an indication that a corrective action should be taken by a user, confirmation of a user-input indication that a corrective action has been completed by a user, and the like. 
     For example, a display device can display, render, or otherwise convey one or more graphical representations or images associated with blood glucose levels, an indication of a change of direction in a blood glucose trend, and/or notifications or alerts associated with blood glucose levels on the display device. In some embodiments, an alert can notify the patient of an over-corrected or under-corrected abnormality. For instance, in one implementation, an alert can be presented via the insulin delivery pump or a manual insulin injection device (e.g., insulin pen), such that the patient is informed that an administered corrective action has not affected the blood glucose levels of the patient in the desired manner (e.g., that the corrective action has over-corrected or under-corrected the abnormality). 
     In some embodiments, an alert can be presented to prompt a user to perform a corrective action, in response to a detected abnormality (e.g., blood glucose levels that are too high or too low). For example, when the abnormality includes blood glucose levels that are too high, the user (patient or health care partner) can be prompted to input a command for the insulin delivery pump to administer a bolus of insulin, via the insulin deliver pump, to treat the high blood glucose levels. Alternatively, a notification can provide health care providers with information to adjust basal rate settings of an inulin infusion device so that they are appropriate for a particular patient to meet their needs. In another embodiment, when the abnormality includes blood glucose levels that are too high, the user (patient or health care partner) can be prompted to input a command at a manual insulin injection device (e.g., insulin pen) to administer insulin. By contrast, when the abnormality includes blood glucose levels that are too low, the alert can prompt the user to administer a dose of carbohydrates to treat the low blood glucose levels. 
     Additionally, the estimated glucose values can be utilized by other downstream systems, such as a fitness or exercise advisor device or application that provides fitness/exercise suggestions or recommendations to users. For instance, the estimated glucose values can be utilized in conjunction with a predicted exercise level in the short future (using similar exercise pattern from the past few minutes) to tell patient if keeping current level of activity will reduce hyperglycemia or introduce hypoglycemia. 
     After  1280 , the method  1280  can loop to the start, and then proceeds to steps  1210 ,  1220  and  1230  to wait and receive new data regarding blood glucose measurements from a blood glucose meter, contextual activity data from an activity tracker and/or other contextual data from other sources and the model would be retrained. 
       FIG.  13    is a block diagram of a workflow process  1300  for generating a personalized model  1350  that is optimized for estimating glucose values for a particular user or patient in accordance with the disclosed embodiments. The workflow process  1300  starts at  1310  where data for multiple users is collected. Examples of this data will be described in greater detail below. At  1320 , population model learning processes can be performed to generate a set of one or more population models. In one non-limiting embodiment, a deep learning network can be used to develop a generic estimation model that is based on learned characteristics of a population of users. Nonlimiting examples of the various processes that can be performed as part of  1320  will be described below with reference to  FIGS.  14  through  22   . 
     At  1330 , at least one of the population models can be selected, and at  1340 , personalized model learning processes can be performed to personalize a selected population model for each particular user. In one non-limiting embodiment, once the population model is developed, the generic, estimation model can be adapted or trained, based on learned characteristics of a particular user (e.g., patient), to generate a personalized estimation model that is optimized for estimating blood glucose of that particular user. The personalized model learning processes  1340  can be performed for any number of users to personalize a population model  1330  selected for each user to generate a personalized model  1350  that is personalized for each user. Nonlimiting examples of the various processes that can be performed as part of  1330  will be described below with reference to  FIGS.  23  through  29   . 
     Once the personalized model is generated it can be used for a variety of purposes including to provide insulin therapy to a particular user without the need for a glucose sensor such as a continuous glucose monitor. 
     Various embodiments of population model learning processes that can be performed will now be described below with reference to  FIGS.  14  through  22   . In those descriptions, like reference numbers refer to similar elements throughout the figures. 
       FIG.  14    is a block diagram of a machine learning system  1400  for generating an optimized population model  1470  for estimating glucose values for a population of users or patients in accordance with the disclosed embodiments. 
     During this part of the workflow process data for multiple users is collected for processing. In this example, the data that is collected can include, but is not limited to, discrete glucose measurement data  1410  from the blood glucose meter or other sensor arrangement that provides discrete glucose measurements, contextual data  1420  from the source of user activity data (e.g., from an activity tracker, electrodermal activity sensor, temperature sensor, oxygen monitor, etc.), and contextual data  1430  from the other sources such as nutritional information about meals consumed by a user, insulin delivered to the user by an insulin infusion device of the user. 
     Data for each of the inputs can be collected for any number of users for a time period. Stated differently, for each user within a population, data can be collected for different input channels. Each of the different input channels can represent a different variable being measured for each user. In some embodiments, the different input channels can include (1) time of day, (2) a blood glucose level, (3) a blood glucose (BG) measurement from a sensor such as a blood glucose meter, activity data including (4) heart rate (beats per minute), (5) METs and (6) number of steps, (7) active insulin, (8) carbohydrates on board, etc. Active insulin can refer to bolus insulin that has already been delivered to a user&#39;s body, but that has not yet been used. An active insulin setting can be considered in determining any active insulin still in a user&#39;s body from their prior boluses and that could continue to lower their blood glucose. 
     In some embodiments, the discrete glucose measurement data  1410 , contextual data  1420  from the source of user activity data and contextual data  1430  from the other sources can then be processed at a population learning processor  1440  to generate the optimized population model  1470 . In this example, as part of the learning process, the population learning processor  1440  can perform various processing tasks with respect to the discrete glucose measurement data  1410  from the blood glucose meter, contextual data  1420  from the source of user activity data and contextual data  1430  from the other sources to generate the optimized population model  1470 . For example, the population learning processor  1440  can apply various machine learning models  1450  including any described herein, such as deep learning models including but not limited to CNNs and RNNs, to the discrete glucose measurement data  1410  from the blood glucose meter, contextual data  1420  from the source of user activity data and contextual data  1430  from the other sources. For instance, in some embodiments, a deep learning network can perform a deep learning process to process a feature matrix to generate a sequence of estimated blood glucose values. 
     The population learning processor  1440  can also perform various parameter optimizations based on the discrete glucose measurement data  1410  from the blood glucose meter, contextual data  1420  from the source of user activity data and contextual data  1430  from the other sources. For example, one or more machine learning or deep learning model(s) can learn the transfer function or mapping from a series of inputs (e.g., discrete glucose measurement data  1410  from the blood glucose meter, contextual data  1420  from the source of user activity data and contextual data  1430  from the other sources) to a glucose measurement from a glucose sensor. This mapping can be on any time interval such that the model estimates anywhere from a single glucose value to a series of glucose values continuous in time. Each machine learning or deep learning model may have one or more parameters that need to be identified to specify the mathematical transfer function. Parameter optimization generally includes an objective function that is minimized. The objective function measures the mathematical agreement between the estimated output of the model with the actual measured data. Parameters are typically interactively adjusted until the objective function is optimized. The optimization process terminates once the level of agreement reaches a desired threshold or no longer improves. 
       FIG.  15    is a block diagram of a windowed machine learning system  1500  for generating an optimized window population model  1570  for estimating glucose values for a population of users or patients in accordance with the disclosed embodiments. The structure of the windowed machine learning system  1500  is similar to the structure of the machine learning system  1400  described above with reference to  FIG.  14   . As such, components or blocks shown in  FIG.  14    will not be described in detail again in conjunction with  FIG.  15   . 
     As in  FIG.  14   , data for multiple users is collected for processing that can include, but is not limited to, discrete glucose measurement data  1510  from the blood glucose meter, contextual data  1520  from the source of user activity data, and contextual data  1530  from the other sources. However, in this embodiment, prior to providing the data to the population learning processor  1540  for processing, the data is provided to a window filter  1535 . The window filter  1535  can split the data into different time windows. In other words, the collected data can be sequentially split or divided into a series of time windows. Each time window can have a period that is less than the overall period that the data was collected over. Each time window includes data that was collected for the different input channels or variables (for each user of the population). 
     In this embodiment, each time window can include a discrete segment of the discrete glucose measurement data  1510 , contextual data  1520  from the source of user activity data and contextual data  1530 . Each time window can then be processed at the population learning processor  1540  to generate the optimized window population model  1570  corresponding to a particular time window. As part of the learning process, the population learning processor  1540  can perform various processing tasks described above with reference to  FIG.  14    except that the tasks are performed on data taken over a particular time window to generate the optimized window population model  1570 . Each instance of the optimized window population model  1570  performs inference on a discrete specified time segment of the input data. For example, in some embodiments, if a window period of two hours is considered, the optimized window population model would be the model that performs best (e.g. lowest error) for input data segmented to two hour periods. 
       FIG.  16    is a block diagram of another windowed machine learning system  1600  for generating an optimized window population model  1670  for estimating glucose values for a population of users or patients in accordance with the disclosed embodiments. The structure of the windowed machine learning system  1600  is similar to the structure of the windowed machine learning systems  1400 ,  1500  described above with reference to  FIGS.  14  and  15   . As such, components or blocks shown in  FIGS.  14  and  15    will not be described in detail again in conjunction with  FIG.  16   . 
     As in  FIGS.  14  and  15   , data for multiple users is collected that can include, but is not limited to, discrete glucose measurement data  1610  from the blood glucose meter, contextual data  1620  from the source of user activity data, and contextual data  1630  from the other sources. Prior to providing the data to the population learning processor  1640  for processing, the data is provided to a window filter  1635  that can split the data into different time windows. Each time window can include a discrete segment of the discrete glucose measurement data  1610 , contextual data  1620  from the source of user activity data and contextual data  1630 . Data from each time window can then be processed at the population learning processor  1640  to generate an output (e.g., set of estimated glucose values) corresponding to a particular time window, as described above with reference to  FIG.  15   . As part of the learning process, the population learning processor  1640  can perform various processing tasks described above with reference to  FIG.  14    except that the tasks are performed on data taken over a particular time window to generate the optimized window population model  1570 . 
     In this embodiment, a window joining processor  1665  is provided that can join sets of the estimated glucose values corresponding to any number of time windows to generate a joined set of estimated glucose values over any number of time windows. For example, in some embodiments, estimated blood glucose sequences over each time window can be stored, and then be sequentially linked together (e.g., assembled/concatenated) at a later time. For example, in some embodiments, estimated blood glucose sequences over each time window can be stored, and when building the model, the stored outputs corresponding to each of the time windows can then be sequentially linked together (e.g., assembled/concatenated) to create the estimation model for the population of users. For example, in some embodiments, if a two hour window filter is considered, the output of the population model (estimated glucose values) would be limited to two hours, as such to generate a longer period output, multiple outputs from multiple windows may be joined. For instance, three two-hour outputs may be joined to generate a six hour model output. In some embodiments, the window joining step takes output of the previous window&#39;s estimated glucose response to initialize the subsequent window. This may be done by replacing or modifying one of the inputs to contain a segment of, or the entire, estimated glucose response output personalized learning step applied to the previous window. 
       FIG.  17    is a block diagram of another windowed machine learning system  1700  for generating an optimized window population model  1770  for estimating glucose values for a population of users or patients in accordance with the disclosed embodiments. The structure of the windowed machine learning system  1700  is similar to the structure of the windowed machine learning system  1400 ,  1500 ,  1600  described above with reference to  FIGS.  14 - 16   . As such, components or blocks shown in  FIGS.  14 - 16    will not be described in detail again in conjunction with  FIG.  17   . 
     As in  FIG.  14 - 16   , data for multiple users is collected that can include, but is not limited to, discrete glucose measurement data  1710  from the blood glucose meter, contextual data  1720  from the source of user activity data, and contextual data  1730  from the other sources. Prior to providing the data to the population learning processor  1740  for processing, the data is provided to a window filter  1735  that can split the data into different time windows. Each time window can include a discrete segment of the discrete glucose measurement data  1710 , contextual data  1720  from the source of user activity data and contextual data  1730 . Data from each time window can then be processed at the population learning processor  1740  to generate an optimized window population model  1570  corresponding to a particular time window, as described above with reference to  FIG.  15   . As part of the learning process, the population learning processor  1740  can perform various processing tasks described above with reference to  FIG.  14    except that the tasks are performed on data taken over a particular time window to generate an output (e.g., set of estimated glucose values) as described with reference to  FIG.  15   . As described with reference to  FIG.  16   , a window joining processor  1765  can join sets of the estimated glucose values corresponding to any number of time windows to generate a joined set of estimated glucose values over any number of time windows. For example, in some embodiments, estimated blood glucose sequences over each time window can be stored, and then be sequentially linked together (e.g., assembled/concatenated) at a later time outputs. In some embodiments, the window joining step takes output of the previous window&#39;s estimated glucose response to initialize the subsequent window. This may be done by replacing or modifying one of the inputs to contain a segment of, or the entire, estimated glucose response output personalized learning step applied to the previous window. 
     In this non-limiting embodiment, the optimized window population model  1670  (generated in  FIG.  16   ) can be processed further by a calibration optimization processor  1766  using the discrete glucose measurement data  1710  to generate an optimized window population model  1770  that has optimized calibration intervals and/or calibration error (e.g., longer intervals between calibration and/or reduced calibration error). The calibration optimization processor  1766  can optimize calibration characteristics such as calibration interval and calibration error by determining which calibration population model will give the provide the best compromise between low calibration error and long calibration interval. In general, the longer the interval the better because it is undesirable to calibrate frequently. The calibration intervals of the optimized window population model  1770  can be optimized by using the discrete glucose measurement data  1710  to adjust the population model output to yield a more accurate estimated glucose. For instance, the adjustment may be made on an interval of minutes, hours, weeks or months. The specific adjustment interval needs may be determined by testing each calibration interval and selecting the population and calibration interval that provides the most accurate glucose estimate. In some embodiments, the calibration interval processor need not rely exclusively on blood glucose meter data, but may in substitute, or in addition, include data from other sources. Processing performed by the calibration optimization processor  1766  will be described in greater detail below with reference to  FIGS.  21  and  22   . 
       FIG.  18    is a block diagram of another windowed machine learning system  1800  for generating an optimized window population model  1870  for estimating glucose values for a population of users or patients in accordance with the disclosed embodiments. The structure of the windowed machine learning system  1800  is similar to the structure of the windowed machine learning systems  1400 ,  1500 ,  1600 ,  1700  described above with reference to  FIGS.  14 - 17   . As such, components or blocks shown in  FIGS.  14 - 17    will not be described in detail again in conjunction with  FIG.  18   . 
     As in  FIG.  14 - 17   , data for multiple users is collected that can include, but is not limited to, discrete glucose measurement data  1810  from the blood glucose meter, contextual data  1820  from the source of user activity data, and other contextual data  1830  from the other sources. Prior to providing the data to the population learning processor  1840  for processing, the data can be provided to a window filter  1835  that can split the data into different time windows. Each time window can include a discrete segment of the discrete glucose measurement data  1810 , contextual data  1820  from the source of user activity data and other contextual data  1830 . Data from each time window can then be processed at the population learning processor  1840  to generate an output (e.g., set of estimated glucose values) corresponding to a particular time window, as described above with reference to  FIG.  15   . As part of the learning process, the population learning processor  1840  can perform various processing tasks described above with reference to  FIG.  14    except that the tasks are performed on data taken over a particular time window to generate an output (e.g., set of estimated glucose values). As described with reference to  FIG.  16   , a window joining processor  1865  can join sets of the estimated glucose values corresponding to any number of time windows to generate a joined set of estimated glucose values over any number of time windows. For example, in some embodiments, estimated blood glucose sequences over each time window can be stored, and then be sequentially linked together (e.g., assembled/concatenated) at a later time. In some embodiments, the window joining step takes output of the previous window&#39;s estimated glucose response to initialize the subsequent window. This may be done by replacing or modifying one of the inputs to contain a segment of, or the entire, estimated glucose response output personalized learning step applied to the previous window. 
     In this embodiment, the optimized window population model  1670  (generated in  FIG.  16   ) can be processed further by a calibration optimization processor  1866  using the discrete glucose measurement data  1810  and/or other data  1867  to generate an optimized window population model  1770  ( FIG.  17   ) that has optimized calibration intervals and/or calibration error (e.g., longer intervals between calibration and/or reduced calibration error). 
     In this embodiment, the other data  1867  can include, for example, one or more past blood glucose meter readings, past glucose sensor data, time and blood glucose value that has the least daily, weekly or monthly variance, past data from any one of the model inputs, etc. Utilizing the other data  1867  in alone or in conjunction with the discrete glucose measurement data  1810  can improve the accuracy and/or calibration interval of the accuracy of the calibration interval of the optimized window population model that is output by the calibration optimization processor  1866 . As described above with respect to the calibration optimization processor  1766 , other data  1867  from other sources may be used in conjunction with or in place of discrete glucose measurement data  1810 . For instance, other data  1867  may provide enough information to provide an accurate calibration method, without the need for invasive blood glucose meter readings. In another instance, to reduce the frequency (lengthen the interval) of blood glucose meter readings, other data  1867  may be used to assist the calibration model to maintain satisfactory performance of the population model accuracy. Processing performed by the calibration optimization processor  1866 , and the variety of inputs or data it can use in place of historical and blood glucose meter data, will be described in greater detail below with reference to  FIGS.  21  and  22   . 
       FIG.  19    is a block diagram of another windowed machine learning system  1900  for generating an optimized window population model  1970  for estimating glucose values for a population of users or patients in accordance with the disclosed embodiments. The structure of the windowed machine learning system  1900  is similar to the structure of the windowed machine learning systems  1400 ,  1500 ,  1600 ,  1700 ,  1800  described above with reference to  FIGS.  14 - 18   . As such, components or blocks shown in  FIGS.  14 - 18    will not be described in detail again in conjunction with  FIG.  19   . 
     As in  FIG.  14 - 18   , data for multiple users is collected that can include, but is not limited to, discrete glucose measurement data  1910  from the blood glucose meter, contextual data  1920  from the source of user activity data, and contextual data  1930  from the other sources. Prior to providing the data to the population learning processor  1940  for processing, the data can be provided to a window filter  1935  that can split the data into different time windows. Each time window can include a discrete segment of the discrete glucose measurement data  1910 , contextual data  1920  from the source of user activity data and contextual data  1930 . Data from each time window can then be processed at the population learning processor  1940  to generate an optimized window population model  1570  corresponding to a particular time window, as described above with reference to  FIG.  15   . As part of the learning process, the population learning processor  1940  can perform various processing tasks described above with reference to  FIG.  14    except that the tasks are performed on data taken over a particular time window to generate an output (e.g., set of estimated glucose values) as described with reference to  FIG.  15   . As described with reference to  FIG.  16   , a window joining processor  1965  can join sets of the estimated glucose values corresponding to any number of time windows to generate a joined set of estimated glucose values over any number of time windows. For example, in some embodiments, estimated blood glucose sequences over each time window can be stored, and then be sequentially linked together (e.g., assembled/concatenated) at a later time. In some embodiments, the window joining step takes output of the previous window&#39;s estimated glucose response to initialize the subsequent window. This may be done by replacing or modifying one of the inputs to contain a segment of, or the entire, estimated glucose response output personalized learning step applied to the previous window. As explained with reference to  FIGS.  17  and  18   , the optimized window population model  1670  (generated in  FIG.  16   ) can be processed further by a calibration optimization processor  1966  using discrete glucose measurement data  1910  and/or other data  1967  to generate an optimized window population model  1770  ( FIG.  17   ) that has optimized calibration intervals and/or calibration error (e.g., longer intervals between calibration and/or reduced calibration error). 
     In this embodiment, the optimized window population model  1870  ( FIG.  18   ) that is output by the calibration optimization processor  1966  can be processed further by a model explainability analysis processor  1968  to generate an optimized window population model  1970  that provides a physiologically consistent response to one or more of the model inputs. For example, the typical human physiological response to food intake is a rise in blood glucose levels. Therefore, each candidate population model may be tested to ensure the response is at least directionally similar, or similar in magnitude, to what is observed clinically, medically, or physiologically. As will be described in greater detail below, the model explainability analysis processor  1968  can modulate or simulate the inputs and compare the observed population model output (or response) to a reference or standard. This comparison may indicate the plausibility and explainability of the model response. This process may remove from consideration all models that fail to respond in an understandable manner. The model explainability analysis processor  1868  can select and output or generate an optimized window population model  1970 . The processing performed by the model explainability analysis processor  1968  will now be described in greater detail below with reference to  FIG.  20   . 
       FIG.  20    is a block diagram of a model explainability analysis processor  2000  for selecting an optimized population model for estimating glucose values for a population of users or patients in accordance with the disclosed embodiments. The model explainability analysis processor  2000  can select an optimized population model from a pool  2080  of candidate population models. The selected optimized population model can then be used as the basis for further training and personalized to generate a personalized model for estimating glucose values for a particular user or patient. 
     During this part of the workflow process data for multiple users can be collected for processing. In this example, the data that is collected can include, but is not limited to, discrete glucose measurement data  2010  from the blood glucose meter, contextual data  2020  from the source of user activity data, and contextual data  2030  from the other sources. 
     The discrete glucose measurement data  2010  from the blood glucose meter, contextual data  2020  from the source of user activity data and contextual data  2030  from the other sources can then be processed at a data modulation processor  2040  to generate a modulated form of the data. For example, in some embodiments, the input data can be modulated (modified) or simulated to generate a change in the content of one or more inputs. The modulated data is executed by a population model to generate the estimated glucose output. In the model response testing step, the output estimated glucose output is compared to a reference or standard that represents the typical directionality or magnitude of a human physiological response to a similar input data modulation. The reference or standard can be, not limited to, documented or general know how of what is typically observed clinically, medically, or physiologically. For example, the typical human physiological response to insulin is a drop in blood glucose levels. Modulation of an insulin input by reduction of the magnitude of the insulin level, in a physiologically accurate model, should result in a lower estimated glucose output. 
     At  2050  through  2060 , the model explainability analysis processor  2000  can then perform processing to evaluate each population model of a number of population models to determine which of those population models should be added to a pool  2080  of candidate population models, and then select (at  2090 ) an optimized population model from the pool  2080  of candidate population models as an optimized population model (e.g., an optimized window population model, an optimized window population model, etc.). At  2050 , the model explainability analysis processor  2000  selects a population model to execute and applies the modulated form of the data to the selected population model to generate a response to the modulated form of the data. At  2055 , the model explainability analysis processor  2000  can perform various tests that help assess or evaluate whether the response (that was generated at  2050 ) is physiologically plausible. At  2060 , the model explainability analysis processor  2000  can then analyze or evaluate the test results generated at  2055  to determine whether the selected population model&#39;s response is a plausible physiological response. When the model explainability analysis processor  2000  determines (at  2060 ) that the test results generated at  2055  indicate that the selected population model&#39;s response is not a plausible physiological response, the model explainability analysis processor  2000  drops the selected population model from further consideration. 
     By contrast, when the model explainability analysis processor  2000  determines (at  2060 ) that the test results generated at  2055  indicate that the selected population model&#39;s response is a plausible physiological response, the model explainability analysis processor  2000  adds the selected population model to a pool  2080  of candidate population models at  2070 . At  2090 , the model explainability analysis processor  2000  can select an optimized population model from the pool  2080  of candidate population models. The selected optimized population model can then be used as the basis for further training and personalized to generate a personalized model for estimating glucose values for a particular user or patient. 
     Referring again to  FIGS.  17  through  19   , the calibration optimization processor  1766 ,  1866 ,  1966  can identify a calibration model that provides the best performance, and also can identify the best type of input to use for developing a calibration model (e.g., selecting the best calibration approach). The processing performed by the calibration optimization processor  1766 ,  1866 ,  1966  will now be described in greater detail below with reference to  FIGS.  21  and  22   . 
       FIG.  21    is a block diagram of a calibration optimization processor  2100  for selecting an optimized calibration model  2170  in accordance with the disclosed embodiments. The calibration optimization processor  2100  can select an optimized calibration model  2170  to be used as the basis for calibrating a population model used for estimating glucose values for a population of users. 
     During this part of the workflow process data can be collected from different potential calibration sources  2110 ,  2120 ,  2130 ,  2140  for processing and evaluation. In this example, the data that is collected can include, but is not limited to, discrete glucose measurement data  2010  collected from a blood glucose meter, historical or sensor glucose trend data  2120 , statistical or heuristic calibration point prediction data  2130 , and glucose value data  2140  from blood glucose reading stability analysis. Historical or sensor glucose trends can include, but not limited to, glucose values from the past, several days of glucose sensor data, time of day point(s) where glucose is less or least variables. Statistical or heuristic calibration point prediction can include, but not limited to, a statistical, empirical, or rule-based method that estimates or predicts the glucose value at a given point in time, which may be used to calibrate the population model. Glucose value from blood glucose reading stability analysis, can include, but not limited to, an analysis of variability of glucose on an hourly, daily, weekly, or monthly basis. The glucose value that is most stable, less or least variable compared to other periods of time, may be selected to calibrate the population model. Each source of data  2110 ,  2120 ,  2130 ,  2140 , or combination thereof, can be applied to a calibrate population model processor  2150  to generate a calibration model that is applied to the population model generating a corresponding calibrated population model response. In other words, while  FIG.  21    illustrates a single arrow between each source of data  2110 ,  2120 ,  2130 ,  2140  and each calibrate population model processor  2150 , it should be appreciated that in other implementations, each source of data  2110 ,  2120 ,  2130 ,  2140  could be linked to each calibrate population model processor  2150 . 
     An error and interval analysis processor  2160  can receive each calibrated population model response. For each calibrated population model response, the error and interval analysis processor  2160  can (1) perform an error analysis and generate an error result that indicates the performance of the calibrated population model response compared to the measured glucose values, and (2) perform an interval analysis to generate an interval result that indicates how often the population model would need to be calibrated with the given input. For each response, the error and interval analysis processor  2160  can then evaluate, the corresponding error result and the corresponding interval result. 
     At  2170 , based on the evaluation of all of the error result/interval result combinations for each type of calibration model, the calibration optimization processor  2100  can compare performance of any given population model for each type of calibration model to determine an optimized calibration model for that given population model. The optimized calibration model can be selected, for example, to minimize error, maximize time between calibrations, and/or reduce user or patient burden. For example, a blood glucose meter reading every few minutes may minimize error but would be burdensome on the user, and as such would have a calibration interval that is too frequent. A blood glucose meter is considered an invasive measurement and thus burdensome to the patient, thus one of the other calibration models based on the alternate input sources that are less invasive or non-invasive may be preferred. The tradeoff between error, calibration interval, and patient burden, may be based on an objective function, clinical criteria, or product, regulatory or business requirements. 
       FIG.  22    is a block diagram of a calibration optimization processor  2200  for selecting optimal type(s) of inputs to be used for developing an optimized calibration model in accordance with the disclosed embodiments. The calibration optimization processor  2200  can select one or more inputs to use with an optimized calibration model when calibrating any given population model used for estimating glucose values for a population of users. 
     During this part of the workflow process data can be collected from different potential calibration sources  2210 ,  2220 ,  2230 ,  2240 ,  2245  for processing and evaluation. In this example, the data that is collected can include, but is not limited to, discrete glucose measurement data  2010  collected from a blood glucose meter, historical or sensor glucose trend data  2220 , statistical or heuristic calibration point prediction data  2230 , glucose value data  2240  from blood glucose reading stability analysis, and contextual data  2245  from the source of user activity data (e.g., an activity tracker), and/or contextual data  2245  from the other sources such as nutritional information about meals consumed by a user, insulin delivered to the user by an insulin infusion device of the user, etc. Historical or sensor glucose trends can include, but not limited to, glucose values from the past, several days of glucose sensor data, time of day point(s) where glucose is less or least variables. Statistical or heuristic calibration point prediction can include, but not limited to, a statistical, empirical, or rule-based method that estimates or predicts the glucose value at a given point in time, which may be used to calibrate the population model. Glucose value from blood glucose reading stability analysis, can include, but not limited to, an analysis of variability of glucose on an hourly, daily, weekly, or monthly basis. The glucose value that is most stable, less or least variable compared to other periods of time, may be selected to calibrate the population model. Each source of data  2210 ,  2220 ,  2230 ,  2240 ,  2245 , or combination thereof, can be applied to a calibrate population model processor  2250  to generate a calibration model that is applied to the population model generating a corresponding calibrated population model response. In other words, while  FIG.  22    illustrates a single arrow between each source of data  2210 ,  2220 ,  2230 ,  2240  and each calibrate population model processor  2250 , it should be appreciated that in other implementations, each source of data  2210 ,  2220 ,  2230 ,  2240  could be linked to each calibrate population model processor  2250 . 
     An error and interval analysis processor  2260  can receive each calibrated population model response. For each calibrated population model response, the error and interval analysis processor  2260  can (1) perform an error analysis and generate an error result that indicates the performance of the calibrated population model response compared to the measured glucose values, and (2) perform an interval analysis to generate an interval result that indicates how often the population model would need to be calibrated with the given input. For each response, the error and interval analysis processor  2260  can then evaluate, the corresponding error result and the corresponding interval result. 
     At  2270 , based on the evaluation of all of the error result/interval result combinations for each type of calibration model, the calibration optimization processor  2200  can compare performance of any given population model for each type of calibration model to determine an optimized calibration model for that given population model. The optimized calibration model can be selected, for example, to minimize error, maximize time between calibrations, and/or reduce user or patient burden. For example, a blood glucose meter reading every few minutes may minimize error but would be burdensome on the user, and as such would have a calibration interval that is too frequent. A blood glucose meter is considered an invasive measurement and thus burdensome to the patient, thus one of the other calibration models based on the alternate input sources that are less invasive or non-invasive may be preferred. The tradeoff between error, calibration interval, and patient burden, may be based on an objective function, clinical criteria, or product, regulatory or business requirements. 
     In this embodiment, once the optimized calibration model is determined (at  2270 ), the calibration optimization processor  2200  can determine or select at  2280 , based on the evaluation of all of the error result/interval result combinations for each type of input, optimal type(s) of inputs to be used with that optimized calibration model (from  2270 ) when it is used for calibrating any given population model. As such, once an optimized calibration model has been determined (at  2270 ), the calibration optimization processor  2200  can select (at  2280 ) one or more types of the inputs  2210 ,  2220 ,  2230 ,  2240 ,  2245  to use with that optimized calibration model. 
     As described above, at least one of the population models can be selected, and personalized model learning processes can be performed to personalize a selected population model for each particular user. Various embodiments of personalized model learning processes that can be performed will now be described below with reference to  FIGS.  23  through  29   . In those descriptions, like reference numbers refer to similar elements throughout the figures. 
       FIG.  23    is a block diagram of a machine learning system  2300  for generating an optimized personal model  2370  for estimating glucose values that are personalized for a particular user or patient in accordance with the disclosed embodiments. During this part of the workflow process data for a particular user is collected for processing. In this example, the data that is collected can include, but is not limited to, discrete glucose measurement data  2310  from the blood glucose meter or other sensor arrangement that provides discrete glucose measurements from the user, contextual data  2320  about the user from the source of user activity data (e.g., an activity tracker), and contextual data  2330  about the user from the other sources such as nutritional information about meals consumed by a user, insulin delivered to the user by an insulin infusion device of the user. 
     Data for each of the inputs can be collected for the particular user over a time period. Stated differently, data for the particular user can be collected for different input channels. Each of the different input channels can represent a different variable being measured for that user. In some embodiments, the different input channels can include (1) time of day, (2) a blood glucose level, (3) a blood glucose (BG) measurement from a sensor such as a CGM device, activity data including (4) heart rate (beats per minute), (5) METs and (6) number of steps, (7) active insulin, (8) carbohydrates on board, etc. 
     In some embodiments, the discrete glucose measurement data  2310 , contextual data  2320  from the source of user activity data and contextual data  2330  from the other sources can then be processed at a personalized learning processor  2340  along with a particular population model  2305  to train or adapt the particular population model  2305  and thus generate the optimized personal model  2370  that is tailored to the particular user or patient. In some embodiments, the particular population model  2305  serves as the machine learning model  2350  and learns based on the inputs  2310 ,  2320 ,  2330  such that the particular population model  2305  is transformed (e.g., re-trained and optimized/personalized to the user) to become the optimized personal model  2370  for estimating glucose values that are personalized for a particular user or patient. In other embodiments, the particular population model  2305  is one model of an ensemble of the machine learning models  2350 , and the ensemble of machine learning models  2350  learns based on the inputs  2310 ,  2320 ,  2330  such that the ensemble is transformed to become the optimized personal model  2370  for estimating glucose values that are personalized for a particular user or patient. In this example, as part of the personalized learning process, the personalized learning processor  2340  can perform various processing tasks with respect to the discrete glucose measurement data  2310  from the blood glucose meter, contextual data  2320  from the source of user activity data and contextual data  2330  from the other sources to train or adapt the particular population model  2305  to generate the optimized personal model  2370 . For example, the personalized learning processor  2340  can apply various machine learning models  2350  including the particular population model  2305 , to the discrete glucose measurement data  2310 , contextual data  2320  from the source of user activity data and the other contextual data  2330  from the other sources to train or adapt the particular population model  2305 . In another embodiment, the particular population model  2305  is combined with a separate personalized model to create an ensemble of population and personalized models that constitute a single optimized personal model. In another embodiment, the particular population model  2305  maybe disregarded and skipped over (e.g., given a zero or near zero weight), in which case the personalized learning processor  2340  can apply other various machine learning models  2350  to generate the optimized personal model  2370  that is tailored to the particular user or patient. 
     The personalized learning processor  2340  can also perform various parameter optimizations based on the discrete glucose measurement data  2310  from the blood glucose meter, contextual data  2320  from the source of user activity data and contextual data  2330  from the other sources to further train the particular population model  2305 . For example, one or more machine learning or deep learning model(s) can learn the transfer function or mapping from a series of inputs to a glucose measurement from a glucose sensor. This mapping can be on any time interval such that the model estimates anywhere from a single glucose value to a series of glucose values continuous in time. Each machine learning or deep learning model may have one or more parameters that need to be identified to specify the mathematical transfer function. Parameter optimization generally includes an objective function that must be minimized. The objective function measures the mathematical agreement between the estimated output of the model with the actual measured glucose values. Parameters are typically interactively adjusted until the objective function is optimized. The optimization process terminates once the level of agreement reaches a desired threshold or no longer improves. 
       FIG.  24    is a block diagram of a windowed machine learning system  2400  for generating an optimized personal model  2470  for estimating glucose values that are personalized for a particular user or patient in accordance with the disclosed embodiments. The structure of the windowed machine learning system  2400  is similar to the structure of the machine learning system  2300  described above with reference to  FIG.  23   . As such, components or blocks shown in  FIG.  23    will not be described in detail again in conjunction with  FIG.  24   . 
     As described above with reference to  FIG.  23   , data for the particular user is collected for processing that can include, but is not limited to, discrete glucose measurement data  2410  from the blood glucose meter, contextual data  2420  from the source of user activity data, and contextual data  2430  from the other sources. However, in this embodiment, prior to providing the data to the personalized learning processor  2440  for processing, the data is provided to a window filter  2435 . The window filter  2435  can split the data into different time windows. In other words, the collected data can be sequentially split or divided into a series of time windows. Each time window can have a period that is less than the overall period that the data was collected over. Each time window includes data that was collected for the different input channels or variables (for each user of the personalized). 
     In this embodiment, each time window can include a discrete segment of the discrete glucose measurement data  2410 , contextual data  2420  from the source of user activity data and contextual data  2430  for the particular user. Each time window can then be processed at the personalized learning processor  2440  to generate the optimized personal model  2470  corresponding to a particular time window. As part of the learning process, the personalized learning processor  2440  can perform various processing tasks described above with reference to  FIG.  23    except that the tasks are performed on data taken over a particular time window to generate the optimized personal model  2470 . Each instance of the optimized personal model  2470  performs inference on a discrete specified time segment of the input data. For example, in some embodiments, if a window period of two hours is considered, the optimal personalized model can be the model that performs best (e.g. lowest error) for input data segmented to two hour periods. 
       FIG.  25    is a block diagram of another windowed machine learning system  2500  for generating an optimized personal model  2570  for estimating glucose values that are personalized for a particular user or patient in accordance with the disclosed embodiments. The structure of the windowed machine learning system  2500  is similar to the structure of the windowed machine learning system  2400  described above with reference to  FIGS.  23  and  24   . As such, components or blocks shown in  FIGS.  23  and  24    will not be described in detail again in conjunction with  FIG.  25   . 
     As in  FIGS.  23  and  24   , data for the particular user is collected that can include, but is not limited to, discrete glucose measurement data  2510  from the blood glucose meter, contextual data  2520  from the source of user activity data, and contextual data  2530  from the other sources. Prior to providing the data to the personalized learning processor  2540  for processing, the data is provided to a window filter  2535  that can split the data into different time windows. Each time window can include a discrete segment of the discrete glucose measurement data  2510 , contextual data  2520  from the source of user activity data and contextual data  2530 . Data from each time window can then be processed at the personalized learning processor  2540  to generate an output (e.g., set of estimated glucose values) corresponding to a particular time window, as described above with reference to  FIG.  24   . As part of the learning process, the personalized learning processor  2540  can perform various processing tasks described above with reference to  FIG.  23    except that the tasks are performed on data taken over a particular time window to generate the optimized personal model  2470 . 
     In this embodiment, a window joining processor  2565  is provided that can join sets of the estimated glucose values corresponding to any number of time windows to generate a joined set of estimated glucose values over any number of time windows. For example, in some embodiments, estimated blood glucose sequences over each time window can be stored, and then be sequentially linked together (e.g., assembled/concatenated) at a later time. For example, in some embodiments, estimated blood glucose sequences over each time window can be stored, and the stored outputs corresponding to each of the time windows can then be sequentially linked together (e.g., assembled/concatenated). In some embodiments, the window joining step takes output of the previous window&#39;s estimated glucose response to initialize the subsequent window. This may be done by replacing or modifying one or more of the inputs to contain a segment of, or the entire, estimated glucose response output personalized learning step applied to the previous window. 
       FIG.  26    is a block diagram of another windowed machine learning system  2600  for generating an optimized personal model  2670  for estimating glucose values that are personalized for a particular user or patient in accordance with the disclosed embodiments. The structure of the windowed machine learning system  2600  is similar to the structure of the windowed machine learning system  2500  described above with reference to  FIGS.  23 - 25   . As such, components or blocks shown in  FIGS.  23 - 25    will not be described in detail again in conjunction with  FIG.  26    unless they perform differently in the embodiment of  FIG.  26   . 
     As in  FIG.  23 - 25   , data for the particular user is collected that can include, but is not limited to, discrete glucose measurement data  2610  from the blood glucose meter, contextual data  2620  from the source of user activity data, and contextual data  2630  from the other sources. Prior to providing the data to the personalized learning processor  2640  for processing, the data is provided to a window filter  2635  that can split the data into different time windows. Each time window can include a discrete segment of the discrete glucose measurement data  2610 , contextual data  2620  from the source of user activity data and contextual data  2630 . Data from each time window can then be processed at the personalized learning processor  2640  to generate an optimized personal model  2470  corresponding to a particular time window, as described above with reference to  FIG.  24   . As part of the learning process, the personalized learning processor  2640  can perform various processing tasks described above with reference to  FIG.  23    except that the tasks are performed on data taken over a particular time window to generate an output (e.g., set of estimated glucose values) as described with reference to  FIG.  24   . As described with reference to  FIG.  25   , a window joining processor  2665  can join sets of the estimated glucose values corresponding to any number of time windows to generate a joined set of estimated glucose values over any number of time windows. For example, in some embodiments, estimated blood glucose sequences over each time window can be stored, and then be sequentially linked together (e.g., assembled/concatenated) at a later time. In some embodiments, the window joining step takes output of the previous window&#39;s estimated glucose response to initialize the subsequent window. This may be done by replacing or modifying one of the inputs to contain a segment of, or the entire, estimated glucose response output personalized learning step applied to the previous window. 
     In this embodiment, the optimized personal model  2570  (generated in  FIG.  25   ) can be processed further by a calibration optimization processor  2666  using the discrete glucose measurement data  2610  and/or other data  2667  to generate an optimized personal model  2670  that has calibration intervals optimized. The calibration intervals of the optimized personal model  2670  can be optimized by using the discrete glucose measurement data  2610 . In some embodiments, the optimized personal model  2570  (generated in  FIG.  25   ) can be processed further by the calibration optimization processor  2666  using discrete glucose measurement data  2610  to generate the optimized personal model  2670 . In other embodiments, calibration optimization processor  2666  can also process other data, such as other data  2667  with or without the discrete glucose measurement data  2610  to generate an optimized personal model  2670 . In some embodiments, the other data  2767  can include at least one or more of, for example, one or more past blood glucose meter readings, past glucose sensor data, time and blood glucose value that has the least daily, weekly or monthly variance, past data from any one of the model inputs, etc. Utilizing the other data  2667  in conjunction with the discrete glucose measurement data  2610  can improve the accuracy of the calibration interval of the optimized personal model that is output by the calibration optimization processor  2666 . Processing performed by the calibration optimization processor  2666  can be performed as described above with reference to  FIGS.  21  and  22   . 
       FIG.  27    is a block diagram of another windowed machine learning system  2700  for generating an optimized personal model  2770  for estimating glucose values for a personalized a particular user or patient in accordance with the disclosed embodiments. The structure of the windowed machine learning system  2700  is similar to the structure of the windowed machine learning system  2600  described above with reference to  FIGS.  23 - 26   . As such, components or blocks shown in  FIGS.  23 - 26    will not be described in detail again in conjunction with  FIG.  27    unless they perform differently in the embodiment of  FIG.  27   . 
     As in  FIG.  23 - 26   , data for the particular user is collected that can include, but is not limited to, discrete glucose measurement data  2710  from the blood glucose meter, contextual data  2720  from the source of user activity data, and contextual data  2730  from the other sources. Prior to providing the data to the personalized learning processor  2740  for processing, the data can be provided to a window filter  2735  that can split the data into different time windows. Each time window can include a discrete segment of the discrete glucose measurement data  2710 , contextual data  2720  from the source of user activity data and contextual data  2730 . Data from each time window can then be processed at the personalized learning processor  2740  to generate an optimized personal model  2470  ( FIG.  24   ) corresponding to a particular time window, as described above with reference to  FIG.  24   . As part of the learning process, the personalized learning processor  2740  can perform various processing tasks described above with reference to  FIG.  23    except that the tasks are performed on data taken over a particular time window to generate the output (e.g., set of estimated glucose values) as described with reference to  FIG.  24   . As described with reference to  FIG.  25   , a window joining processor  2765  can join sets of the estimated glucose values corresponding to any number of time windows to generate a joined set of estimated glucose values over any number of time windows. For example, in some embodiments, estimated blood glucose sequences over each time window can be stored, and then be sequentially linked together (e.g., assembled/concatenated) at a later time. In some embodiments, the window joining step takes output of the previous window&#39;s estimated glucose response to initialize the subsequent window. This may be done by replacing or modifying one of the inputs to contain a segment of, or the entire, estimated glucose response output personalized learning step applied to the previous window. 
     As explained with reference to  FIG.  26   , in some embodiments, the optimized personal model  2570  (generated in  FIG.  25   ) can be processed further by a calibration optimization processor  2766  to generate an optimized personal model  2670  ( FIG.  26   ). 
     In this embodiment, the optimized personal model that is output by the calibration optimization processor  2766  can then be processed further by the model explainability analysis processor  2768  to generate an optimized personal model  2770  that provides a physiologically consistent response to one or more of the model inputs. For example, the typical human physiological response to food intake is a rise in blood glucose levels. Therefore, each candidate population model may be tested to ensure the response is at least directionally similar, or similar in magnitude, to what is observed clinically, medically, or physiologically. As described with reference to  FIGS.  19  and  20   , the model explainability analysis processor  2768  can modulate or simulate the inputs and compare the observed personal model output (or response) to a reference or standard. This comparison may indicate the plausibility and explainability of the model response. This process may remove from consideration all models that fail to respond in an understandable manner. The model explainability analysis processor  2768  can select and output or generate an optimized window population model  1970 . 
       FIG.  28    is a block diagram that illustrates an intermittent CGM system  2800  in accordance with the disclosed embodiments. The system  2800  includes a personalized model  2840  and a calibration model  2850 . The personalized model  2840  can refer to any type of personalized model including the optimized and windowed personal models described above. Once the personalized model  2840  and the calibration model  2850  have been properly trained they can be deployed and utilized by a particular user or patient. Once deployed, input data for the particular user can be received continuously. In this embodiment, this input data can include, but is not limited to, discrete glucose measurement data  2810  from the blood glucose meter for that particular user or patient, contextual data  2820  from the source of user activity data for that particular user or patient, and contextual data  2830  from the other sources for that particular user or patient. The personalized model  2840  can receive and process the input data to generate a continuous time-series of estimated glucose values  2870 . The estimated glucose values  2870  can then be used for a variety of purposes. For instance, as one non-limiting example, the estimated glucose values  2870  can be used in conjunction with an insulin infusion system to provide CGM-like therapy to the particular user or patient without the need for glucose sensor. The calibration model  2850  can be used to calibrate personalized model  2840  to help improve the performance of the model and ensure that it is performing accurately. 
       FIG.  29    is a block diagram that illustrates another intermittent CGM system  2900  in accordance with the disclosed embodiments. The structure of the intermittent CGM system  2900  is similar to the structure of the intermittent CGM system  2800  described above with reference to  FIG.  28   . As such, components or blocks shown in  FIG.  28    will not be described in detail again in conjunction with  FIG.  29    unless they perform differently in the embodiment of  FIG.  28   . In this embodiment, prior to providing the input data to the personalized model  2940  for processing, the data is provided to a window filter  2935  that can split the input data into different time windows. Each time window can include a discrete segment of the discrete glucose measurement data  2910  for that particular user or patient, contextual data  2920  from the source of user activity data for that particular user or patient, and contextual data  2930  for that particular user or patient. Data from each time window can then be processed at the personalized model  2940  to generate a time-series of estimated glucose values  2970  corresponding to a particular time window. In some embodiments, a window joining processor  2965  is provided that can join sets of the estimated glucose values  2970  corresponding to any number of time windows to generate a joined set of estimated glucose values  2970  over any number of time windows. For example, in some embodiments, estimated blood glucose sequences over each time window can be stored, and then be sequentially linked together (e.g., assembled/concatenated) at a later time. In some embodiments, the window joining step takes output of the previous window&#39;s estimated glucose response to initialize the subsequent window. This may be done by replacing or modifying one of the inputs to contain a segment of, or the entire, estimated glucose response output personalized learning step applied to the previous window. 
     While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or embodiments described herein are not intended to limit the scope, applicability, or configuration of the claimed subject matter in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the described embodiment or embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope defined by the claims, which includes known equivalents and foreseeable equivalents at the time of filing this patent application.