## 8 Glucose Measurement  
Glucose measurement (GM) is one of the fundamental components of modern AP systems. It is extremely important to monitor the glucose levels in the human blood for transparent management and early diagnosis of diabetes as well as an endocrine metabolic disorder [172]. Furthermore, GM plays a vital role in yielding near-normal glycemic control which is extremely important to prevent diabetes. Continuous monitoring of the glucose levels empowers faster treatment decisions, steps to be taken to prevent fluctuations in the BG levels, and to avoid further complications in a human body [173; 174]. Recently, due to significant developments in sensor technology, low-cost sensors have been extensively used for GM purposes [175]. In addition, edge computing and fog computing are two latest architectures for a sensor's data handling that can offload data from the cloud, process it in a T1 DM patient, and transmit information machine-to-human or machine-to-machine in just a few milliseconds or seconds [176]. [PERSON] et al. [177] described the detailed understanding about the GM, methods used for the GM, and calibration methods used for the sensor's readings correction for T1 DM's control and treatment. The patients of T1 DM can monitor their GM via two methods, (i) self-monitoring blood glucose (SMBG) using home blood glucose meters or (ii) using a CGM to monitor the glucose concentrations continuously [178]. The GM provides the data essential to make daily administration and management decisions related to the insulin dose, food intake, and physical exercise etc. The recent introduction of the CGM enables the GM subcutaneously in interstitial fluid which has a range of advantages compared to the SMBG method. The SMBG test strips were available in the market from approximately 35 years ago. The latest SMBG test strips contains hexokinase or glucose oxidase chemistry and can yield a numerical measure of capillary glucose concentration either via photometry, colorimetry, or electrochemistry after a series of chemical reactions on a small drop of blood (<1 uL for some meters). Nearly 30 home BG meters are obtainable from the market today. All SMBG meters satisfy the minimum standards of accuracy as established by the FDA. Despite the success of the CGM, the SMBG remains the most usual form of glucose monitoring and GM practiced by T1 DM patients in recent times. In contrast, the CGM provides the time-series glucose data which is highly reliable whereas the SMBG gives only snapshots of the BG's concentration. The CGM can report \(\sim\)288 glucose values per day and produce data revealing temporal trends and patterns in the glucose control. The CGM technologies measure glucose subcutaneously, in the interstitial fluid. A sensor is positioned just under the patient'sskin typically in the patients' thighs, buttocks, upper-arm, or abdomen. The sensor is a glucose oxidase platinum electrode [179], which generates an electrical current in the presence of glucose in the interstitial fluid. Each individual CGM monitors measure the electrical current and generates an average glucose value every five minutes which, depending on the monitor, is either displayed in real-time or stored for later downloading. In order to receive or either display or record glucose values, calibration is required for accurate monitoring and analysis [179; 180]. Furthermore, in case of the real-time CGM, monitors can be programmed to trigger alerts/alarms for both high or low glucose values, thus permitting T1 DM patients to treat for these abnormal readings and significantly reducing fear related to hypo or hyperglycemia [181]. The advantages and disadvantages of both GM techniques used in real-world applications are summarized in Table 2.  
[PERSON] et al. [183] described various GM techniques including CGM and SMBG, guidelines on the use of both CGM and SMBG, and metrics used in the CGM evaluation. Furthermore, they described the latest CGM devices that can overcome the limitations of the HbA1c monitoring and SMBG. [PERSON] et al.