Measurement Performance of Two Continuous Tissue Glucose Monitoring Systems Intended for Replacement of Blood Glucose MonitoringParts of the data have previously been presented at the 77th Scientific Sessions of the American Diabetes Association in San Diego, CA; June 9–13, 2017 and at the 17th Annual Diabetes Technology Meeting in Bethesda, MD, November 2–4, 2017.Trial number: DRKS00011920; registered at the Deutsches Register Klinischer Studien (German clinical trials register), an approved Primary Regis

Abstract

Background: Currently, two systems for continuous tissue glucose monitoring (CGM) (Dexcom® G5 [DG5] and FreeStyle Libre [FL]) are intended to replace blood glucose monitoring (BGM) and, according to manufacturer labeling, are distributed as such in some jurisdictions, including the United States and the European Union.Methods: The measurement performance of these two systems in comparison with a BGM system was analyzed in a 14-day study with 20 participants comprising study site visits, which included phases of induced rapid glucose changes, and home use phases. Performance analysis was mainly based on deviations between CGM readings and BGM results. Sensor-to-sensor precision was also analyzed.Results: Approximately 25% of DG5 and FL results showed differences from BGM results exceeding 15 mg/dL or 15% (at glucose concentration below or above 100 mg/dL, respectively) at times of therapeutic decisions, and ∼5% of differences exceeded 30 mg/dL or 30%. Performance was different depending on the setting (study site visits, home use phases, and phases of induced rapid glucose changes). In consensus error grid (CEG) analysis, both systems showed >99.5% of results within the clinically acceptable zones A and B.Conclusions: In this study, both systems showed deviations from blood glucose (BG) measurements, the current standard approach in diabetes therapy. Although a large percentage of results was found in CEG zones A and B, for approximately one in four therapeutic decisions, CGM and BG readings differed by at least 15 mg/dL or 15%. Such deviations should be taken into account when using CGM systems.

Differences Between Flash Glucose Monitor and Fingerprick Measurements

“…Several studies have reported an overall performance of the FL comparable to that of other state-of-the-art CGM systems [7,20,21,22,23,24,25,26,27,28,29]. Our main results are in line with previous observations as we find an overall MARD of 12.3% and half of the participants having a MARD at or below 10%.…”

“…This is an obvious follow up question to the present study. Answering this question would require a study with at least two FL sensors per person, for instance as in the study performed by Freckmann et al [29], where each of the 20 participants wore two FL sensors and two DexCom G5 sensors (DG5), and SMBG was measured every hour during three clinic visits. A larger between-sensor discrepancy was seen in FL than in DG5, as measured by Precision Absolute Relative Difference (PARD), and it was seen that four of 20 participants had a PARD ≥ 15.…”

Switching from Flash Glucose Monitoring to Continuous Glucose Monitoring on Hypoglycemia in Adults with Type 1 Diabetes at High Hypoglycemia Risk: The Extension Phase of the I HART CGM Study

“…Other data suggest that accuracy of flash and RT-CGM is comparable across a wide glucose range, including below hypoglycemia thresholds. 20 , 21 We recognize the importance of a standard reference methodology when comparing different interstitial glucose monitoring technologies in clinical trials.…”

National Consensus in the use of the Flash Glucose Monitoring System in Portugal

“…29 The precision of the two different systems -Dexcom G5 and FreeStyle Libre -seem to be similar. 30 The recommendations that existed until now, briefly discussed below, are essentially based on the experience of experts, of people with diabetes, and on the few available clinical studies. [31][32][33][34][35] There are two types of recommendations for insulin dose adjustments based on trend arrows: the first recommendation is based on a percentage correction to the usual insulin doses, while the second takes into account the 'predicted' glucose value at the end of a set period of time.…”