Feasibility of an Orthogonal Redundant Sensor incorporating Optical plus Redundant Electrochemical Glucose Sensing

Abstract

For people with type 1 diabetes (T1D), matching insulin delivery to their varying insulin requirements is central to maximizing quality of life and minimizing diabetes complications.1,2 In contrast to glucose meters, 3 continuous glucose monitoring (CGM) systems measuring interstitial fluid (ISF) glucose provide near-continuous real-time glucose information. 4 CGM improves glycemia for adults with T1D 5,6 and provides a vital component in artificial pancreas development. 7 However, CGM technology remains less accurate than the most accurate glucose meters, 8 with mean absolute relative differences (MARDs) of current generation CGM between 10 and 18%. 9 To replace fingerstick measurement, and to achieve sufficient functionality for use in an artificial pancreas system, CGM needs improved accuracy and reliability.629982D STXXX10.1177/1932296816629982Journal Abstract Background: Orthogonal redundancy for glucose sensing (multiple sensing elements utilizing distinct methodologies) may enhance performance compared to nonredundant sensors, and to sensors with multiple elements utilizing the same technology (simple redundancy). We compared the performance of a prototype orthogonal redundant sensor (ORS) combining optical fluorescence and redundant electrochemical sensing via a single insertion platform to an electrochemical simple redundant sensor (SRS).Methods: Twenty-one adults with type 1 diabetes wore an ORS and an SRS concurrently for 7 days. Following sensor insertion, and on Day 4 with a standardized meal, frequent venous samples were collected for reference glucose measurement (laboratory [YSI] and meter) over 3 and 4 hours, respectively. Between study visits reference capillary blood glucose testing was undertaken. Sensor data were processed prospectively.Results: ORS mean absolute relative difference (MARD) was (mean ± SD) 10.5 ± 13.2% versus SRS 11.0 ± 10.4% (P = .34). ORS values in Clarke error grid zones A and A+B were 88.1% and 97.6%, respectively, versus SRS 86.4% and 97.8%, respectively (P = .23 and P = .84). ORS Day 1 MARD (10.7 ± 10.7%) was superior to SRS (16.5 ± 13.4%; P < .0001), and comparable to ORS MARD for the week. ORS sensor survival (time-averaged mean) was 92.1% versus SRS 74.4% (P = .10). ORS display time (96.0 ± 5.8%) was equivalent to SRS (95.6 ± 8.9%; P = .87). Conclusions:Combining simple and orthogonal sensor redundancy via a single insertion is feasible, with accuracy comparing favorably to current generation nonredundant sensors. Addition of an optical component potentially improves sensor reliability compared to electrochemical sensing alone. Further improvement in optical sensing performance is required prior to clinical application. 10,11,13 Nonelectrochemical CGM modalities including optical technologies have been explored, 10,11 though none are currently commercially available. One promising optical methodology is fluorescence-based sensing involving reversible competitive binding between a fluorophore-labeled glucose receptor and a glucose analog. Keywords14 Relative to ele...

Modeling the Error of the Medtronic Paradigm Veo Enlite Glucose Sensor

“…Day 1 infers that the sensor has been very recently inserted, while day 7 is near the end of the life of the sensor. Therefore, day 4 (standard working modality), which is not affected by the Foreign Body Response (FBR) or sensor hydration in the early stages of insertion [ 28 , 29 ] nor biofouling in the later stages of the sensor life [ 30 ], is the most appropriate day to compare to the ENL sensor on day 2. These values of variance are lower than those of the 7P, G4P, and G4AP sensors.…”

Human-in-the-Loop Insulin Dosing

“…Multiple CGMs, of different types (optical and electrochemical), are under development and add redundancy. 18,19 Improved closed-loop performance is possible if other sensors are used, particularly accelerometers for exercise (and sleep) detection. 20-22 Further, accelerometers (and gyroscopes) in a wristwatch worn on the dominant hand can be used to detect meal motions to provide an advisory “meal announcement.” Exercise and meals can also be anticipated based on history, GPS, and calendar information and using artificial intelligence and deep learning techniques.…”

Moving Toward a Unified Platform for Insulin Delivery and Sensing of Inputs Relevant to an Artificial Pancreas

“…Our research group investigated a prototype orthogonal redundant sensor that combined an optical fluorescence sensor with two electrochemical sensing elements via a single insertion platform. 6 This demonstrated a trend to improved sensor accuracy and reliability, and while promising, further technical development of the optical sensing component is needed to fulfill the potential of this approach.…”

“…In the future greater demands are likely to be placed upon skin insertion sites, with closed-loop systems infusing more than one hormone, redundant glucose sensors, and the potential requirement for sensors measuring molecules other than glucose. [5][6][7] The burden associated with CGM wear is evident in both clinical practice and clinical trials, where individuals with type 1 diabetes frequently wear their glucose sensors much less than 100% of the time. 8 Minimizing the physical presence and increasing sensor accuracy may increase patient acceptance and utilization of such systems.…”

“…In the future greater demands are likely to be placed upon skin insertion sites, with closed-loop systems infusing more than one hormone, redundant glucose sensors, and the potential requirement for sensors measuring molecules other than glucose. 5-7…”