Continuous Glucose Monitoring Sensors: Past, Present and Future Algorithmic Challenges

Abstract

Continuous glucose monitoring (CGM) sensors are portable devices that allow measuring and visualizing the glucose concentration in real time almost continuously for several days and are provided with hypo/hyperglycemic alerts and glucose trend information. CGM sensors have revolutionized Type 1 diabetes (T1D) management, improving glucose control when used adjunctively to self-monitoring blood glucose systems. Furthermore, CGM devices have stimulated the development of applications that were impossible to create without a continuous-time glucose signal, e.g., real-time predictive alerts of hypo/hyperglycemic episodes based on the prediction of future glucose concentration, automatic basal insulin attenuation methods for hypoglycemia prevention, and the artificial pancreas. However, CGM sensors’ lack of accuracy and reliability limited their usability in the clinical practice, calling upon the academic community for the development of suitable signal processing methods to improve CGM performance. The aim of this paper is to review the past and present algorithmic challenges of CGM sensors, to show how they have been tackled by our research group, and to identify the possible future ones.

Clinical Implications of Accuracy Measurements of Continuous Glucose Sensors

“…24 However, improvements in software alone have also demonstrated significant improvement in MARD. 25 Variability among manufacturer lots and between day of wear (i.e., first day performance is typically worse than subsequent days) 26 are other confounders when attempting to characterize sensor accuracy. Despite these pitfalls, it is generally appreciated that MARD-characterized accuracy in CGMs has steadily improved over the years.…”

“…Although today's CGMs are clearly more accurate than earlier CGMs, 25 reliably assessing the comparative accuracy among today's CGMs presents a challenge. Few head-tohead studies exist in the literature 11,27 because of limited resources, including sparse on-body space to place comparator sensors.…”

“…In silico simulations can randomize thousands of virtual patients to sensors of varying accuracy to explore the impact of device characteristics on insulin dosing and glycemia. 25 The recent approval of Dexcom's G5 CGM for nonadjuctive use was largely based on both its lower MARD and two in silico simulations. 6 The first 2-week simulation study utilized a validated physiological model to compare CGM-based and SMBGbased testing time in a range <50 mg/dL and >250 mg/dL.…”

Wearable Continuous Glucose Monitoring Sensors: A Revolution in Diabetes Treatment

“…Present challenges in medical research include, for instance, the assessment of the clinical benefits brought by CGM sensors in diabetes management. From the technological point of view, examples of research activities include the exploration of principles alternative to glucose-oxidase, such as fluorescence and skin dielectric properties [14], ergonomics [15], data/signal processing [16], and software development [17] to mention a few. The aim of this paper is to provide an overview of the current status of CGM sensors and to discuss future scenarios of diabetic therapy and the technologies, hardware and software.…”

Study of Electrochemical Impedance of a Continuous Glucose Monitoring Sensor and its Correlation With Sensor Performance

“…Such devices use electrochemical sensors to measure metabolites in a fast, inexpensive and reliable way. A notable example that is commercially available is continuous glucose measurement (CGM) device that uses enzymatic electrochemical glucose sensor for management of diabetes [3].…”