Hydrogel Glucose Sensor with In Vivo Stable Fluorescence Intensity Relying on Antioxidant Enzymes for Continuous Glucose Monitoring.
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ABSTRACT:
SUBMITTER: Sawayama J
PROVIDER: S-EPMC7306611 | biostudies-literature | 2020 Jun
REPOSITORIES: biostudies-literature
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Project description:This study evaluated the accuracy and performance of a fourth-generation subcutaneous glucose sensor (Guardian™ Sensor 3) in the abdomen and arm.Eighty-eight subjects (14-75 years of age, mean?±?standard deviation [SD] of 42.0?±?19.1 years) with type 1 or type 2 diabetes participated in the study. Subjects wore two sensors in the abdomen that were paired with either a MiniMed™ 640G insulin pump, or an iPhone® or iPod® touch® running a glucose monitoring mobile application (Guardian Connect system) and a third sensor in the arm, which was connected to a glucose sensor recorder (GSR). Subjects were also asked to undergo in-clinic visits of 12-14?h on study days 1, 3, and 7 for frequent blood glucose sample testing using a Yellow Springs Instrument (YSI) reference.The overall mean absolute relative difference (MARD?±?SD) between abdomen sensor glucose (SG) and YSI reference values was 9.6%?±?9.0% and 9.4%?±?9.8% for the MiniMed 640G insulin pump and Guardian Connect system, respectively; and 8.7%?±?8.0% between arm SG and YSI reference values. The percentage of SG values within 20% agreement of the YSI reference value (for YSI >80?mg/dL) was 90.7% with the MiniMed 640G insulin pump, 91.8% with the Guardian Connect system, and 93.1% for GSR-connected arm sensors. Mean functional sensor life, when calibrating 3-4 times/day, was 145.9?±?39.3?h for sensors paired with the MiniMed 640G insulin pump, 146.1?±?41.6?h for sensors paired with the Guardian Connect system, and 147.6?±?40.4?h for sensors connected to the GSR. Responses to survey questions regarding sensor comfort and ease of use were favorable.The Guardian Sensor 3 glucose sensor, whether located in abdomen or the arm, provided accurate glucose readings when compared with the YSI reference and demonstrated functional life commensurate with the intended 7-day use. ClinicalTrials.gov : NCT02246582.
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Project description:BackgroundThe level of continuous glucose monitoring (CGM) accuracy needed for insulin dosing using sensor values (i.e., the level of accuracy permitting non-adjunct CGM use) is a topic of ongoing debate. Assessment of this level in clinical experiments is virtually impossible because the magnitude of CGM errors cannot be manipulated and related prospectively to clinical outcomes.Materials and methodsA combination of archival data (parallel CGM, insulin pump, self-monitoring of blood glucose [SMBG] records, and meals for 56 pump users with type 1 diabetes) and in silico experiments was used to "replay" real-life treatment scenarios and relate sensor error to glycemic outcomes. Nominal blood glucose (BG) traces were extracted using a mathematical model, yielding 2,082 BG segments each initiated by insulin bolus and confirmed by SMBG. These segments were replayed at seven sensor accuracy levels (mean absolute relative differences [MARDs] of 3-22%) testing six scenarios: insulin dosing using sensor values, threshold, and predictive alarms, each without or with considering CGM trend arrows.ResultsIn all six scenarios, the occurrence of hypoglycemia (frequency of BG levels ≤50 mg/dL and BG levels ≤39 mg/dL) increased with sensor error, displaying an abrupt slope change at MARD =10%. Similarly, hyperglycemia (frequency of BG levels ≥250 mg/dL and BG levels ≥400 mg/dL) increased and displayed an abrupt slope change at MARD=10%. When added to insulin dosing decisions, information from CGM trend arrows, threshold, and predictive alarms resulted in improvement in average glycemia by 1.86, 8.17, and 8.88 mg/dL, respectively.ConclusionsUsing CGM for insulin dosing decisions is feasible below a certain level of sensor error, estimated in silico at MARD=10%. In our experiments, further accuracy improvement did not contribute substantively to better glycemic outcomes.
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