Abstract:
A diabetes care management system for managing blood glucose levels associated with diabetes comprising a computing device and an insulin delivery device. The computing device generally includes (i) a memory comprising one or more optimal blood glucose values, one or more self care values of a patient, one or more measured blood glucose values, and one or more scaling factors for weighting the impact on a future blood glucose value and that are customizable to an individual patient to predict the effect on the blood glucose of self care actions performed by the individual patient; (ii) a microprocessor, in communication with the memory, programmed to (A) determine the one or more scaling factors from one or more physiological parameters including body mass, metabolism rate, fitness level or hepatic or peripheral insulin sensitivity, or combinations thereof, and (B) calculate a further value, the further value being based on the self care values, and on the one or more optimal blood glucose values, and on the one or more scaling factors; and (iii) a display configured to display information according to the further value; and (iv) a housing, wherein the memory and the microprocessor are housed within the housing, thereby providing a hand-held, readily transportable computing device. The insulin delivery device may deliver insulin in response to information associated with the further value.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of Ser. No. 11/926,675, filed Oct. 29, 2007 now U.S. Pat. No. 7,979,259, which is a continuation of Ser. No. 11/656,168, filed Jan. 22, 2007 now U.S. Pat. No. 7,979,688, which is a continuation of application Ser. No. 09/810,865, filed Mar. 16, 2001, now U.S. Pat. No. 7,167,818, which is a continuation of Ser. No. 09/399,122, filed Sep. 20, 1999, now U.S. Pat. No. 6,233,539, which is a continuation of Ser. No. 08/781,278 filed Jan. 10, 1997, now U.S. Pat. No. 5,956,501, each of which are herein incorporated by reference. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The present invention relates generally to disease simulation systems, and in particular to a system and method for simulating a disease control parameter and for predicting the effect of patient self-care actions on the disease control parameter. 
     2. Description of Prior Art 
     Managing a chronic disease or ongoing health condition requires the monitoring and controlling of a physical or mental parameter of the disease. Examples of these disease control parameters include blood glucose in diabetes, respiratory flow in asthma, blood pressure in hypertension, cholesterol in cardiovascular disease, weight in eating disorders, T-cell or viral count in HIV, and frequency or timing of episodes in mental health disorders. Because of the continuous nature of these diseases, their corresponding control parameters must be monitored and controlled on a regular basis by the patients themselves outside of a medical clinic. 
     Typically, the patients monitor and control these parameters in clinician assisted self-care or outpatient treatment programs. In these treatment programs, patients are responsible for performing self-care actions which impact the control parameter. Patients are also responsible for measuring the control parameter to determine the success of the self-care actions and the need for further adjustments. The successful implementation of such a treatment program requires a high degree of motivation, training, and understanding on the part of the patients to select and perform the appropriate self-care actions. 
     One method of training patients involves demonstrating the effect of various self-care actions on the disease control parameter through computerized simulations. Several computer simulation programs have been developed specifically for diabetes patients. Examples of such simulation programs include BG Pilot™ commercially available from Raya Systems, Inc. of 2570 El Camino Real, Suite 520, Mountain View, Calif. 94040 and AIDA freely available on the World Wide Web at the Diabetes UK website http://www.pcug.co.uk/diabetes/aida.htm. 
     Both BG Pilot™ and AIDA use mathematical compartmental models of metabolism to attempt to mimic various processes of a patient&#39;s physiology. For example, insulin absorption through a patient&#39;s fatty tissue into the patient&#39;s blood is represented as a flow through several compartments with each compartment having a different flow constant. Food absorption from mouth to stomach and gut is modeled in a similar manner. Each mathematical compartmental model uses partial differential equations and calculus to simulate a physiological process. 
     This compartmental modeling approach to disease simulation has several disadvantages. First, understanding the compartmental models requires advanced mathematical knowledge of partial differential equations and calculus which is far beyond the comprehension level of a typical patient. Consequently, each model is an unfathomable “black box” to the patient who must nevertheless trust the model and rely upon it to learn critical health issues. 
     A second disadvantage of the compartmental modeling approach is that a new model is needed for each new disease to be simulated. Many diseases involve physiological processes for which accurate models have not been developed. Consequently, the mathematical modeling approach used in BG Pilot™ and AIDA is not sufficiently general to extend simulations to diseases other than diabetes. 
     A further disadvantage of the modeling approach used in BG Pilot™ and AIDA is that the mathematical models are not easily customized to an individual patient. As a result, BG Pilot™ and AIDA are limited to simulating the effect of changes in insulin and diet on the blood glucose profile of a typical patient. Neither of these simulation programs may be customized to predict the effect of changes in insulin and diet on the blood glucose profile of an individual patient. 
     OBJECTS AND ADVANTAGES OF THE INVENTION 
     In view of the above, it is an object of the present invention to provide a disease simulation system which is sufficiently accurate to teach a patient appropriate self-care actions and sufficiently simple to be understood by the average patient. It is another object of the invention to provide a disease simulation system which may be used to simulate many different types of diseases. A further object of the invention is to provide a disease simulation system which may be easily customized to an individual patient. 
     These and other objects and advantages will become more apparent after consideration of the ensuing description and the accompanying drawings. 
     SUMMARY OF THE INVENTION 
     The invention presents a system and method for simulating a disease control parameter and for predicting the effect of patient self-care actions on the disease control parameter. According to the method, a future disease control parameter value X(t i ) at time t j  is determined from a prior disease control parameter value X(t i ) at time t i  based on an optimal control parameter value R(t j ) at time t j , the difference between the prior disease control parameter value X(t i ) and an optimal control parameter value R(t i ) at time t i , and a set of differentials between patient self-care parameters having patient self-care values S M (t i ) at time t i  and optimal self-care parameters having optimal self-care values O M (t i ) at time t i . In the preferred embodiment, the differentials are multiplied by corresponding scaling factors K M  and the future disease control parameter value X(t j ) is calculated according to the equation: 
     
       
         
           
             
               X 
               ⁡ 
               
                 ( 
                 
                   t 
                   j 
                 
                 ) 
               
             
             = 
             
               
                 R 
                 ⁡ 
                 
                   ( 
                   
                     t 
                     j 
                   
                   ) 
                 
               
               + 
               
                 ( 
                 
                   
                     X 
                     ⁡ 
                     
                       ( 
                       
                         t 
                         i 
                       
                       ) 
                     
                   
                   - 
                   
                     R 
                     ⁡ 
                     
                       ( 
                       
                         t 
                         i 
                       
                       ) 
                     
                   
                 
                 ) 
               
               + 
               
                 
                   ∑ 
                   M 
                 
                 ⁢ 
                 
                   
                     K 
                     M 
                   
                   ⁡ 
                   
                     ( 
                     
                       
                         
                           S 
                           M 
                         
                         ⁡ 
                         
                           ( 
                           
                             t 
                             i 
                           
                           ) 
                         
                       
                       - 
                       
                         
                           O 
                           M 
                         
                         ⁡ 
                         
                           ( 
                           
                             t 
                             i 
                           
                           ) 
                         
                       
                     
                     ) 
                   
                 
               
             
           
         
       
     
     A preferred system for implementing the method includes an input device for entering the patient self-care values S M (t i ). The system also includes a memory for storing the optimal control parameter values R(t i ) and R(t j ), the prior disease control parameter value X(t i ), the optimal self-care values O M (t i ), and the scaling factors K M . A processor in communication with the input device and memory calculates the future disease control parameter value X(t j ). A display is connected to the processor to display the future disease control parameter value X(t j ) to a patient. 
     In the preferred embodiment, the system further includes a recording device in communication with the processor for recording an actual control parameter value A(t i ) at time t i , an actual control parameter value A(t j ) at time t j , and actual self-care parameters having actual self-care values C M (t i ) at time t i . The processor adjusts the scaling factors K M  based on the difference between the actual control parameter value A(t j ) and the optimal control parameter value R(t j ), the difference between the actual control parameter value A(t i ) and the optimal control parameter value R(t i ), and the difference between the actual self-care values C M (t i ) and the optimal self-care values O M (t i ). Thus, the scaling factors K M  are customized to an individual patient to predict the effect on the disease control parameter of self-care actions performed by the individual patient. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of a simulation system according to the invention. 
         FIG. 2  is a sample physiological parameter entry screen according to the invention. 
         FIG. 3  is a sample self-care parameter entry screen according to the invention. 
         FIG. 4  is a table of values according to the invention. 
         FIG. 5  is a sample graph of disease control parameter values created from the table of  FIG. 4 . 
         FIG. 6  is another table of values according to the invention. 
         FIG. 7  is a sample graph of disease control parameter values created from the table of  FIG. 6 . 
         FIG. 8  is another table of values according to the invention. 
         FIG. 9  is a sample graph of disease control parameter values created from the table of  FIG. 8 . 
         FIG. 10  is a schematic illustration of the entry of actual parameter values in a recording device of the system of  FIG. 1 . 
         FIG. 11  is a schematic diagram of another simulation system according to the invention. 
         FIG. 12  is a schematic block diagram illustrating the components of the system of  FIG. 11 . 
         FIG. 13  is a flow chart illustrating steps included in a method of the invention. 
         FIG. 14  is a flow chart illustrating steps included in another method of the invention. 
     
    
    
     DESCRIPTION 
     The present invention is a system and method for simulating a disease control parameter and for predicting an effect of patient self-care actions on the disease control parameter. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that these specific details need not be used to practice the invention. In other instances, well known structures, interfaces, and processes are not shown in detail to avoid unnecessarily obscuring the present invention. 
       FIGS. 1-10  illustrate a preferred embodiment of a simulation system according to the invention. The following table illustrates a representative sampling of the types of diseases, patient self-care parameters, and disease control parameters which may be simulated using the system and method of the invention. 
     
       
         
               
               
               
             
           
               
                   
               
               
                 Disease 
                 Self-Care Parameters 
                 Control Parameter 
               
               
                   
               
             
             
               
                 Diabetes 
                 insulin, diet, exercise 
                 blood glucose level 
               
               
                 Asthma 
                 allergens, exercise, inhaled 
                 peak flow rate 
               
               
                   
                 bronchial dilators, anti- 
               
               
                   
                 inflammatory medications 
               
               
                 Obesity 
                 diet, exercise, metabolism 
                 weight 
               
               
                   
                 altering medications 
               
               
                 Hypertension 
                 diet, exercise, stress 
                 blood pressure 
               
               
                   
                 reduction, blood pressure 
               
               
                   
                 medications 
               
               
                 Coronary Artery 
                 diet, exercise, stress 
                 cholesterol 
               
               
                 Disease 
                 reduction, lipid lowering 
               
               
                   
                 medications 
               
               
                 Panic Disorder 
                 stress reduction, anti- 
                 number of episodes 
               
               
                   
                 depressant medications 
               
               
                 Nicotine Addiction 
                 cigarettes smoked, coping 
                 urges to smoke 
               
               
                   
                 behaviors 
               
               
                   
               
             
          
         
       
     
     The above table is not intended as an exhaustive list, but merely as a representative sampling of the types of diseases and disease control parameters which may be simulated. For simplicity, the preferred embodiment is described with reference to a single disease, diabetes, having a single disease control parameter, a blood glucose level. However, it is to be understood that the system and method of the invention are sufficiently flexible to simulate any disease which has a measurable control parameter and which requires patient self-care actions. 
     Referring to  FIG. 1 , a simulation system generally indicated at  10  includes a server  12  having a processor and memory for executing a simulation program which will be described in detail below. Server  12  is in communication with a healthcare provider computer  14  through a network link  48 . 
     Healthcare provider computer  14  is preferably a personal computer located at a healthcare provider site, such as a doctor&#39;s office. 
     Server  12  is also in communication with a patient multi-media processor  24  through a network link  50 . Patient multi-media processor  24  is located at a patient site, typically the patient&#39;s home. In the preferred embodiment, server  12  is a world wide web server, multi-media processor  24  is a web TV processor for accessing the simulation program on server  12 , and links  48  and  50  are Internet links. Specific techniques for establishing client/server computer systems in this manner are well known in the art. 
     Healthcare provider computer  14  includes a processor and memory, a standard display  16 , and a keyboard  20 . Computer  14  further includes a card slot  18  for receiving a data storage card, such as a smart card  22 . Computer  14  is designed to read data from card  22  and write data to card  22 . Patient multi-media processor  24  includes a corresponding card slot  26  for receiving card  22 . Processor  24  is designed to read data from card  22  and write data to card  22 . Thus, healthcare provider computer  14  communicates with patient multi-media processor  24  via smart card  22 . Such smart card data communication systems are also well known in the art. 
     Multi-media processor  24  is connected to a display unit  28 , such as a television, by a standard connection cord  32 . Display unit  28  has a screen  30  for displaying simulations to the patient. An input device  34 , preferably a conventional hand-held remote control unit or keyboard, is in signal communication with processor  24 . Device  34  has buttons or keys  36  for entering data in processor  24 . 
     System  10  also includes an electronic recording device  38  for recording actual control parameter values and patient self-care data indicating actual self-care actions performed by the patient. Recording device  38  includes a measuring device  40  for producing measurements of the disease control parameter, a keypad  44  for entering the self-care data, and a display  42  for displaying the control parameter values and self-care data to the patient. 
     Recording device  38  is preferably portable so that the patient may carry device  38  and enter the self-care data at regular monitoring intervals. Device  38  is further connectable to healthcare provider computer  14  via a standard connection cord  46  so that the control parameter values and patient self-care data may be uploaded from device  38  to computer  14 . Such recording devices for producing measurements of a disease control parameter and for recording self-care data are well known in the art. For example, U.S. Pat. No. 5,019,974 issued to Beckers on May 28, 1991 discloses such a recording device. 
     In the example of the preferred embodiment, the disease control parameter is the patient&#39;s blood glucose level and recording device  38  is a blood glucose meter, as shown in  FIG. 10 . In this embodiment, measuring device  40  is a blood glucose test strip designed to test blood received from a patient&#39;s finger  54 . Device  38  is also designed to record values of the patient&#39;s diet, medications, and exercise durations entered by the patient through keypad  44 . Of course, in alternative embodiments, the recording device may be a peak flow meter for recording a peak flow rate, a cholesterol meter for recording a cholesterol level, etc. 
     The simulation system of the present invention includes a simulation program which uses a mathematical model to calculate disease control parameter values. The following variables used in the mathematical model are defined as follows: 
     N=Normal time interval in which patient self-care actions are employed to make a measurable difference in the disease control parameter or a natural rhythm occurs in the disease control parameter. For diabetes and asthma, time interval N is preferably twenty-four hours. For obesity or coronary artery disease, time interval N is typically three to seven days. 
     t 1 , t 2 , . . . t i , t j  . . . t N =Time points at which the disease control parameter is measured by a patient. For a daily rhythm control parameter such as a blood glucose level, the time points are preferably before and after meals. For weight or cholesterol control parameters, the time points are preferably once a day or once every second day. 
     X(t)=Simulated disease control parameter value at time t determined by the simulation program. 
     R(t)=Optimal control parameter value at time t expected as a normal rhythm value of the disease control parameter at time t if the patient performs optimal self-care actions in perfect compliance from time t j  to the time point immediately preceding time t. 
     A(t)=actual control parameter value at time t measured by the patient. 
     O M (t i )=Optimal self-care parameter values O 1 (t i ), O 2 (t i ), . . . O m (t i ) at time t i  expected to produce optimal control parameter value R(t j ) at time t j . For example, a diabetes patient&#39;s optimal self-care parameter values include a prescribed dose of insulin, a prescribed intake of carbohydrates, and a prescribed exercise duration. 
     S M (t i )=Patient self-care parameter values S 1 (t i ), S 2 (t i ), . . . S m (t i ) at time t i  entered in the simulation system by the patient to simulate self-care actions. 
     C M (t i )=Actual self-care parameter values C 1 (t i ), C 2 (t i ), . . . C m (t i ) at time t i  indicating actual self-care actions performed by the patient at time t i . 
     K M =Corresponding scaling factors K 1 (t i ), K 2 (t i ), . . . K m  for weighting the impact on a future disease control parameter value X(t j ) at time t j  which results from differentials between patient self-care values S M (t i ) and corresponding optimal self-care values O M (t i ). 
     With these definitions, future disease control parameter value X(t j ) is calculated according to the equation: 
     
       
         
           
             
               X 
               ⁡ 
               
                 ( 
                 
                   t 
                   j 
                 
                 ) 
               
             
             = 
             
               
                 R 
                 ⁡ 
                 
                   ( 
                   
                     t 
                     j 
                   
                   ) 
                 
               
               + 
               
                 ( 
                 
                   
                     X 
                     ⁡ 
                     
                       ( 
                       
                         t 
                         i 
                       
                       ) 
                     
                   
                   - 
                   
                     R 
                     ⁡ 
                     
                       ( 
                       
                         t 
                         i 
                       
                       ) 
                     
                   
                 
                 ) 
               
               + 
               
                 
                   ∑ 
                   M 
                 
                 ⁢ 
                 
                   
                     K 
                     M 
                   
                   ⁡ 
                   
                     ( 
                     
                       
                         
                           S 
                           M 
                         
                         ⁡ 
                         
                           ( 
                           
                             t 
                             i 
                           
                           ) 
                         
                       
                       - 
                       
                         
                           O 
                           M 
                         
                         ⁡ 
                         
                           ( 
                           
                             t 
                             i 
                           
                           ) 
                         
                       
                     
                     ) 
                   
                 
               
             
           
         
       
     
     Future disease control parameter value X(t j ) at time t j  is determined from a prior disease control parameter value X(t i ) at time t i  based on an optimal control parameter value R(t j ) at time t j , the difference between prior disease control parameter value X(t i ) and an optimal control parameter value R(t i ) at time t i , and a set of differentials between patient self-care values S M (t i ) and optimal self-care values O M (t i ). The differentials are multiplied by corresponding scaling factors K M . 
     Thus, as patient self-care parameter values S M (t i ) deviate from optimal self-care parameter values O M (t i ), future disease control parameter value X(t j ) deviates from optimal control parameter value R(t j ) by an amount proportional to scaling factors K M . This mathematical model follows the patient&#39;s own intuition and understanding that if the patient performs optimal self-care actions in perfect compliance, the patient will achieve the optimal control parameter value at the next measurement time. However, if the patient deviates from the optimal self-care actions, the disease control parameter value will deviate from the optimal value at the next measurement time. 
     The simulation program is also designed to generate an entry screen for entry of the patient self-care parameter values.  FIG. 3  shows a sample patient self-care parameters entry screen  52  as it appears on display unit  28 . The patient self-care parameters include a food exchange parameter expressed in grams of carbohydrates consumed, an insulin dose parameter expressed in units of insulin injected, and an exercise duration parameter expressed in fifteen minute units of exercise performed. 
     These self-care parameters are illustrative of the preferred embodiment and are not intended to limit the scope of the invention. Many different self-care parameters may be used in alternative embodiments. Screen  52  contains data fields  53  for entering a food exchange parameter value S 1 (t), an insulin dose parameter value S 2 (t), and an exercise duration parameter value S 3 (t). Each data field  53  has a corresponding time field  51  for entering a time point corresponding to the patient self-care parameter value. Screen  52  also includes an OK button  55  and a cancel button  57  for confirming and canceling, respectively, the values entered in screen  52 . 
       FIG. 4  shows a sample table of values  56  created by the simulation program using the data entered by the patient through the self-care parameters entry screen. Table  56  includes a column of simulated disease control parameter values calculated by the simulation program, as will be explained in the operation section below. The simulation program is further designed to generate graphs of simulated disease control parameter values.  FIG. 5  illustrates a sample graph  58  generated from table  56  as it appears on screen  30  of the display unit. Specific techniques for writing a simulation program to produce such a graph are well known in the art. 
     In the preferred embodiment, healthcare provider computer  14  is programmed to determine scaling factors K M  from values of physiological parameters of the patient.  FIG. 2  shows a sample physiological parameter entry screen  41  as it appears on the healthcare provider computer. The physiological parameters of the patient include a body mass, a metabolism rate, a fitness level, and hepatic and peripheral insulin sensitivities. These physiological parameters are illustrative of the preferred embodiment and are not intended to limit the scope of the invention. Many different physiological parameters may be used in alternative embodiments. Screen  41  includes data fields  43  for entering physiological parameter values, an OK button  45  for confirming the values, and a cancel button  47  for canceling the values. 
     Healthcare provider computer  14  stores indexes for determining the scaling factors from the physiological parameters entered. For example,  FIG. 4  shows an insulin sensitivity scaling factor K 2  corresponding to insulin dose parameter value S 2 (t). Computer  14  is programmed to determine from a stored insulin index a value of scaling factor K 2  based on the entered values of the patient&#39;s body mass and insulin sensitivities. In this example, computer  14  determines a value of −40 for scaling factor K 2 , indicating that for this patient, one unit of insulin is expected to lower the patient&#39;s blood glucose level by 40 mg/dL. Computer  14  is programmed to determine the remaining scaling factors in a similar manner. The specific indexes required to determine the scaling factors from values of a patient&#39;s physiological parameters are well known in the art. 
     In the preferred embodiment, healthcare provider computer  14  is also programmed to adjust scaling factors K M  based on the difference between an actual control parameter value A(t j ) measured at time t j  and optimal control parameter value R(t j ), the difference between an actual control parameter value A(t i ) measured at time t i  and optimal control parameter value R(t i ), and the difference between actual self-care values C M (t i ) performed by the patient at time t i  and optimal self-care values O M (t i ). 
     Scaling factors K M  are adjusted to fit the mathematical model presented above, preferably using a least squares, chi-squares, or similar regressive fitting technique. Specific techniques for adjusting coefficients in a mathematical model are well known in the art. For example, a discussion of these techniques is found in “Numerical Recipes in C: The Art of Scientific Computing”, Cambridge University Press, 1988. 
     The operation of the preferred embodiment is illustrated in  FIG. 13 .  FIG. 13  is a flow chart illustrating a preferred method of using system  10  to simulate the disease control parameter. In step  200 , optimal self-care values and optimal control parameter values for each time point are determined for the patient, preferably by the patient&#39;s healthcare provider. The optimal self-care values and optimal control parameter values are then entered and stored in provider computer  14 . 
     In the preferred embodiment, the optimal self-care values include an optimal food exchange parameter value O 1 (t) expressed in grams of carbohydrates, an optimal insulin dose parameter value O 2 (t) expressed in units of insulin, and an optimal exercise duration parameter value O 3 (t) expressed in fifteen minute units of exercise. Specific techniques for prescribing optimal self-care values and optimal control parameter values for a patient are well known in the medical field. 
     In step  202 , the healthcare provider determines the physiological parameter values of the patient and enters the physiological parameter values in computer  14  through entry screen  41 . As shown in  FIG. 2 , the physiological parameter values include a body mass, a metabolism rate, a fitness level, and hepatic and peripheral insulin sensitivities. Specific techniques for testing a patient to determine these physiological parameter values are also well known in the medical field. 
     Following entry of the physiological parameter values, computer  14  determines scaling factors K M  from the stored indexes, step  204 . For example,  FIG. 4  shows a food exchange scaling factor K 1  corresponding to food exchange parameter value S 1 (t), an insulin sensitivity scaling factor K 2  corresponding to insulin dose parameter value S 2 (t), and an exercise duration scaling factor K 3  corresponding to exercise duration parameter value S 3 (t). 
     In this example, computer  14  determines a value of 4 for scaling factor K 1 , a value of −40 for scaling factor K 2 , and a value of −5 for scaling factor K 3 . These values indicate that one gram of carbohydrate is expected to raise the patient&#39;s blood glucose level by 4 mg/dL, one unit of insulin is expected to lower the patient&#39;s blood glucose level by 40 mg/dL, and fifteen minutes of exercise is expected to lower the patient&#39;s blood glucose level by 5 mg/dL. Of course, these values are just examples of possible scaling factors for one particular patient. The values of the scaling factors vary between patients in dependence upon the physiological parameter values determined for the patient. 
     The determined optimal self-care values, optimal control parameter values, and scaling factors are then stored on smart card  22 , step  206 . Typically, the values are stored on smart card  22  during a patient visit to the healthcare provider. The patient then takes home smart card  22  and inserts smart card  22  in patient multi-media processor  24 , step  208 . Next, the patient accesses the simulation program on server  12  through multi-media processor  24 , step  210 . 
     The simulation program generates self-care parameters entry screen  52 , which is displayed to the patient on screen  30  of display unit  28 . In step  212 , the patient enters patient self-care values S M (t) and corresponding time points in data fields  53  and  51 , respectively, using input device  34 . The optimal self-care values, optimal control parameter values, scaling factors, and patient self-care values are transmitted from multi-media processor  24  to server  12  through link  50 . In step  214 , the simulation program calculates simulated disease control parameter values at each time point according to the equation: 
     
       
         
           
             
               X 
               ⁡ 
               
                 ( 
                 
                   t 
                   j 
                 
                 ) 
               
             
             = 
             
               
                 R 
                 ⁡ 
                 
                   ( 
                   
                     t 
                     j 
                   
                   ) 
                 
               
               + 
               
                 ( 
                 
                   
                     X 
                     ⁡ 
                     
                       ( 
                       
                         t 
                         i 
                       
                       ) 
                     
                   
                   - 
                   
                     R 
                     ⁡ 
                     
                       ( 
                       
                         t 
                         i 
                       
                       ) 
                     
                   
                 
                 ) 
               
               + 
               
                 
                   ∑ 
                   M 
                 
                 ⁢ 
                 
                   M 
                   ⁡ 
                   
                     ( 
                     
                       
                         
                           S 
                           M 
                         
                         ⁡ 
                         
                           ( 
                           
                             t 
                             i 
                           
                           ) 
                         
                       
                       - 
                       
                         
                           O 
                           M 
                         
                         ⁡ 
                         
                           ( 
                           
                             t 
                             i 
                           
                           ) 
                         
                       
                     
                     ) 
                   
                 
               
             
           
         
       
     
     Thus, each future disease control parameter value X(t j ) is calculated from optimal control parameter value R(t j ), the difference between prior disease control parameter value X(t i ) and optimal control parameter value R(t i ), and the set of differentials between patient self-care values S M (t i ) and optimal self-care values O M (t i ). The differentials are multiplied by corresponding scaling factors K M . In the preferred embodiment, first simulated disease control parameter value X(t 1 ) at time t j  is set equal to first optimal control parameter value R(t 1 ) at time t 1 . In an alternative embodiment, first simulated disease control parameter value X(t 1 ) is determined from the last disease control parameter value calculated in a prior simulation. 
       FIGS. 4-5  illustrate a first example of simulated disease control parameter values calculated by the simulation program. Referring to  FIG. 4 , the simulation program creates table of values  56  having a time column, an optimal control parameter value column, a simulated control parameter value column, three self-care value differential columns indicating differentials between patient self-care parameter values and optimal self-care parameter values, and three corresponding scaling factor columns for weighting the corresponding self-care value differentials. 
     Table  56  illustrates the simplest simulation, in which the patient follows the optimal self-care actions in perfect compliance at each time point. In this simulation, each patient self-care parameter value equals its corresponding optimal self-care parameter value, so that the simulated disease control parameter value at each time point is simply equal to the optimal control parameter value at each time point. Referring to  FIG. 5 , the simulation program generates graph  58  of the simulated disease control parameter values. 
     Graph  58  is displayed to the patient on screen  30  of display unit  28 , step  216 . 
       FIGS. 6-7  illustrate a second example of simulated disease control parameter values calculated by the simulation program.  FIG. 6  shows a table of values  59  having identical structure to table  56 . Table  59  illustrates a simulation in which the patient consumes  10  extra grams of carbohydrates at 8:00 and exercises for 60 extra minutes at 15:00. In this simulation, the differential S 1 (t)-O 1 (t) is equal to 10 at 8:00 due to the 10 extra grams of carbohydrates consumed by the patient. 
     Because scaling factor K 1  equals 4, the simulation program calculates simulated disease control parameter value X(t 2 ) at time point 10:00 as 40 mg/dL higher than optimal control parameter value R(t 2 ) at 10:00. 
     Similarly, the differential S 3 (t)-O 3 (t) is equal to 4 at time point 15:00 due to the 60 extra minutes of exercise performed by the patient. With simulated disease control parameter value X(t 4 ) exceeding optimal control parameter value R(t 4 ) by 40 mg/dL at 15:00 and with scaling factor K 3  equal to −5, the simulation program calculates simulated disease control parameter value X(t 5 ) at time point 18:00 as 20 mg/dL higher than optimal control parameter value R(t 5 ).  FIG. 7  shows a graph  60  of the simulated-disease control parameter values determined in table  59 . Graph  60  is displayed to the patient on screen  30  of the display unit. 
       FIGS. 8-9  illustrate a third example of simulated disease control parameter values calculated by the simulation program. Referring to  FIG. 8 , a table of values  61  illustrates a simulation in which the patient consumes  10  extra grams of carbohydrates at 8:00, injects 1 extra unit of insulin at 10:00, and exercises for 60 extra minutes at 15:00. The differential S 2 (t)-O 2 (t) is equal to 1 at 10:00 due to the 1 extra unit of insulin injected by the patient. With simulated disease control parameter value X(t 2 ) exceeding optimal control parameter value R(t 2 ) by 40 mg/dL at 10:00, and with scaling factor K 2  equal to −40, the simulation program calculates simulated disease control parameter value X(t 3 ) at time point 12:00 as equal to optimal control parameter value R(t 3 ).  FIG. 8  shows a graph  62  of the simulated disease control parameter values determined in table  61 . 
     In addition to performing simulations with the simulation program, the patient records actual control parameter values and actual self-care values indicating actual self-care actions performed by the patient at each time point, step  218 . These values are preferably recorded in recording device  38 . Upon the patient&#39;s next visit to the healthcare provider, the actual control parameter values and actual self-care values are uploaded to provider computer  14 , step  220 . Those skilled in the art will appreciate that recording device  38  may also be networked to provider computer  14  through a modem and telephone lines or similar network connection. In this alternative embodiment, the actual control parameter values and actual self-care values are transmitted directly from the patient&#39;s home to provider computer  14 . 
     In step  222 , provider computer  14  adjusts scaling factors K M  based on the difference between the actual control parameter values and the optimal control parameter values at each time point and the difference between the actual self-care values and the optimal self-care values at each time point. Scaling factors K M  are adjusted to fit them to the actual patient data recorded. In this manner, the scaling factors are customized to the individual patient to enable the patient to run customized simulations. The new values of the scaling factors are stored on smart card  22  which the patient takes home and inserts in processor  24  to run new simulations. 
       FIGS. 11-12  illustrate a second embodiment of the invention. The second embodiment differs from the preferred embodiment in that the components of the simulation system are contained in a single stand-alone computing device  64 . The second embodiment also differs from the preferred embodiment in that the system predicts each future disease control parameter value from an actual measured disease control parameter value rather than from a prior simulated disease control parameter value. 
     Referring to  FIG. 11 , computing device  64  includes a housing  66  for holding the components of device  64 . Housing  66  is sufficiently compact to enable device  64  to be hand-held and carried by a patient. Device  64  also includes measuring device  40  for producing measurements of actual control parameters values and a display  70  for displaying data to the patient. Device  64  further includes a keypad  68  for entering in device  64  the optimal control parameter values, the optimal self-care values, the patient self-care parameter values, the actual self-care parameter values, and the patient&#39;s physiological parameter values. 
       FIG. 12  shows a schematic block diagram of the components of device  64  and their interconnections. Device  64  has a microprocessor  72  and a memory  74  operably connected to microprocessor  72 . Measuring device  40  and display  70  are also connected to microprocessor  72 . Keypad  68  is connected to microprocessor  72  through a standard keypad decoder  78 . Microprocessor  72  is connected to an input/output port  76  for entering in device  64  a simulation program to be executed by microprocessor  72  which will be explained in detail below. 
     Memory  74  stores the optimal control parameter values, the optimal self-care values, the patient self-care parameter values, the actual self-care parameter values C M (t), the scaling factors, and the patient&#39;s physiological parameter values. Memory  74  also stores the simulation program to be executed by microprocessor  72  and the indexes for calculating the scaling factors from the patient&#39;s physiological parameter values. 
     In the second embodiment, microprocessor  72  is programmed to perform the functions performed by the healthcare provider computer of the preferred embodiment. The functions include determining scaling factors K M  from the patient&#39;s physiological parameter values. The functions also include adjusting scaling factors K M  based on the difference between actual control parameter value A(t j ) and optimal control parameter value R(t j ), the difference between actual control parameter value A(t i ) and optimal control parameter value R(t i ), and the difference between actual self-care values C M (t i ) and optimal self-care values O M (t i ). 
     The operation of the second embodiment is shown in  FIG. 14 .  FIG. 14  is a flow chart illustrating a preferred method of using the system of the second embodiment to predict an effect of patient self-care actions on a disease control parameter. In step  300 , the optimal control parameter values and optimal self-care values are entered in device  64  and stored in memory  74 . The optimal control parameter values and optimal self-care values may be entered in device  64  either through keypad  68  or through input/output port  76 . 
     In step  302 , the patient or healthcare provider determines the patient&#39;s physiological parameter values. The physiological parameter values are then entered in device  64  through keypad  68  and stored in memory  74 . Following entry of the physiological parameter values, microprocessor  72  determines scaling factors K M  from the indexes stored in memory  74 , step  304 . Scaling factors K M  are then stored in memory  74 . In an alternative method of determining and storing scaling factors K M  in memory  74 , scaling factors K M  are determined in a healthcare provider computer, as previously described in the preferred embodiment. Scaling factors K M  are then entered in device  64  through keypad  68  or port  76  and stored in memory  74 . 
     In step  306 , the patient enters in microprocessor  72  actual disease control parameter A(t i ). To enter actual disease control parameter A(t i ), the patient places his or her finger on measurement device  40  at time t i . Measurement device  40  produces a measurement of actual disease control parameter A(t i ) which is stored in memory  74 . In step  308 , the patient enters in microprocessor  72  patient self-care values S M (t i ) using keypad  68 . In step  310 , microprocessor  72  executes the simulation program stored in memory  74  to calculate future disease control parameter value X(t j ). 
     The simulation program of the second embodiment differs from the simulation program of the preferred embodiment in that future disease control parameter value X(t j ) is calculated from actual disease control parameter A(t i ) rather than from a prior simulated disease control parameter value. In the second embodiment, future disease control parameter value X(t j ) is calculated according to the equation: 
     
       
         
           
             
               X 
               ⁡ 
               
                 ( 
                 
                   t 
                   j 
                 
                 ) 
               
             
             = 
             
               
                 R 
                 ⁡ 
                 
                   ( 
                   
                     t 
                     j 
                   
                   ) 
                 
               
               + 
               
                 ( 
                 
                   
                     A 
                     ⁡ 
                     
                       ( 
                       
                         t 
                         i 
                       
                       ) 
                     
                   
                   - 
                   
                     R 
                     ⁡ 
                     
                       ( 
                       
                         t 
                         i 
                       
                       ) 
                     
                   
                   + 
                   
                     
                       ∑ 
                       M 
                     
                     ⁢ 
                     
                       
                         K 
                         M 
                       
                       ⁡ 
                       
                         ( 
                         
                           
                             
                               S 
                               M 
                             
                             ⁡ 
                             
                               ( 
                               
                                 t 
                                 i 
                               
                               ) 
                             
                           
                           - 
                           
                             
                               O 
                               M 
                             
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             
                               ( 
                               
                                 t 
                                 i 
                               
                               ) 
                             
                           
                         
                         ) 
                       
                     
                   
                 
               
             
           
         
       
     
     Thus, future disease control parameter value X(t j ) is determined from optimal control parameter value R(t i ), the difference between actual disease control parameter A(t i ) and optimal control parameter value R(t i ), and the set of differentials between patient self-care values S M (t i ) and optimal self-care values O M (t i ). The differentials are multiplied by corresponding scaling factors K M . Future disease control parameter value X(t j ) is displayed to the patient on display  70 , step  312 . 
     Once future disease control parameter value X(t j ) is displayed to the patient, the patient uses the value to select appropriate actual self-care actions to perform at time t i . Alternatively, the patient may perform several more simulations of future disease control parameter value X(t j ) to decide appropriate self-care actions to perform at time t i . Once the patient has performed the self-care actions, the patient enters in microprocessor  72  actual self-care values C M (t i ) indicating the self-care actions performed, step  314 . The actual self-care values are then stored in memory  74 . 
     The patient also enters in microprocessor  72  actual disease control parameter A(t j ) measured at time t j . To enter actual disease control parameter A(t j ) the patient places his or her finger on measurement device  40  at time t j . Measurement device  40  produces a measurement of actual disease control parameter A(t j ) which is stored in memory  74 , step  316 . In step  318 , microprocessor  72  adjusts scaling factors K M  based on the difference between actual control parameter value A(t j ) and optimal control parameter value R(t j ), the difference between actual control parameter value A(t i ) and optimal control parameter value R(t i ), and the difference between actual self-care values C M (t i ) and optimal self-care values O M (t i ). In this manner, the scaling factors are customized to the individual patient to enable the patient to run customized simulations. The new values of the scaling factors are stored in memory  74  and used by microprocessor  72  in subsequent simulations. 
     Summary, Ramifications, and Scope 
     Although the above description contains many specificities, these should not be construed as limitations on the scope of the invention but merely as illustrations of some of the presently preferred embodiments. Many other embodiments of the invention are possible. For example, the preferred embodiment is described in relation to diabetes. However, the system and method of the invention may be used for simulating any disease which has a measurable control parameter and which requires patient self-care actions. Similarly, the self-care parameters, corresponding scaling factors, and physiological parameters described are exemplary of just one possible embodiment. Many different self-care parameters, scaling factors, and physiological parameters may be used in alternative embodiments. 
     The preferred embodiment also presents a simulation system that includes a server, a healthcare provider computer, and patient multi-media processor communicating with the provider computer via a smart card. This configuration of system components is presently preferred for ease of setting, storing, and adjusting the model parameters and scaling factors under the supervision of a healthcare provider. However, those skilled in the art will recognize that many other system configurations are possible. For example, in one alternative embodiment, the system is configured as a single stand-alone computing device for executing simulations. 
     In another embodiment, the smart card is eliminated from the simulation system. In this embodiment, the model parameter values and scaling factors are transmitted directly to the server from the healthcare provider computer. In a further embodiment, the provider computer is also eliminated and the recording device is networked directly to the server. In this embodiment, the server is programmed to set, store, and adjust the model parameters and scaling factors based on patient data received through the recording device and patient multi-media processor. 
     In yet another embodiment, the server is eliminated and the simulation program is run on the patient multi-media processor. In this embodiment, the recording device and multi-media processor may also be networked directly to the provider computer, eliminating the need for a smart card. Specific techniques for networking computers and recording devices in these alternative system configurations are well known in the art. 
     Further, the first embodiment is described as a system for simulating a disease control parameter from simulated data and the second embodiment is described as a system for predicting a future value of a disease control parameter from actual patient data. These systems are presented in separate embodiments for clarity of illustration and ease of understanding. However, it is anticipated that both embodiments could be combined into a single simulation system for simulating disease control parameter values from simulated data, actual-patient data, or a combination of simulated and actual data. 
     Therefore, the scope of the invention should be determined not by the examples given but by the appended claims and their legal equivalents.