1299-OR: Concordance of Libre, Dexcom, and Medtronic Glucose Management Indicator (GMI) and Laboratory HbA1c

Introduction and Objective: A recent study comparing Freestyle Libre (FSL) 3, Dexcom (Dex) G7, and Medtronic (Med) Simplera CGM systems found discordant glycaemic metrics, with Med showing a significantly lower glucose management indicator (GMI) and a higher time-in-range. The purpose of this study was to assess concordance between laboratory HbA1c and GMI from three sensor families (Dex G6/G7; FSL L2/L2+/L3/L3+ and Med Guardian4/Simplera) under real-world conditions. Methods: Retrospective, observational, three-centre study of adults with type 1 diabetes (n=349, age 43±14, duration of diabetes 25±13) treated with a range of automated insulin delivery (AID) systems, comprising FSL (n=50), Dex (n=212), and Med sensors (n=87). We assessed glycaemic metrics for 90 days preceding the date of the lab A1c. Results: All three sensor families showed good overall GMI alignment with Lab A1c [%], with a glucose-variability (CV%) adjusted mean deviation of <0.2%. [GMI-Lab A1c; Mean, 95% CI; Dex +0.18% (+0.11, +0.26); FSL -0.02% (-0.17, +0.13); Med -0.16% (-0.28, -0.05), p < 0.001 with difference between Dex and the other two sensors, and no difference between Med and the FSL family. Bland-Altman plots for the three sensor families (Figure) show broadly similar patterns. Conclusion: We show good alignment between 90-day GMI and Lab A1c across all three sensor families under real-world conditions. We did not detect a clinically significant systematic bias towards lower GMI with Medtronic sensors. Disclosure L. Farouk: None. B. Bashir: None. R. Seese: None. P. Avari: Research Support; Current; Dexcom, Inc., Diabetes UK. M. Reddy: Research Support; Current; Dexcom, Inc., Medtronic, Roche Diabetes Care. Advisory Panel; Ended; Medtronic. N. Oliver: Research Support; Current; Dexcom, Inc., Roche Diabetes Care. Speaker's Bureau; Current; Sanofi. Speaker's Bureau; Ended; AstraZeneca. Research Support; Current; Medtronic. Speaker's Bureau; Ended; Dexcom, Inc. M. Evans: Other - Triallist, speaker, advisory board; Current; Abbott Diabetes. Other - Research support, speaker, advisory board; Current; Novo Nordisk A/S. Other - Triallist, advisory board, speaker; Current; Sanofi. Other - Triallist, speakers fees; Current; Eli Lilly and Company. Other - Triallist, advisory board; Current; Medtronic. Other - Advisory board; Current; Dexcom, Inc. Advisory Panel; Current; Zucara Therapeutics, vTv Therapeutics. Other - Advisory panel, triallist; Current; Pila Pharma. H. Thabit: Speaker's Bureau; Ended; Eli Lilly and Company. Speaker's Bureau; Current; Insulet Corporation. Research Support; Current; Dexcom, Inc. Advisory Panel; Current; Roche Diabetes Care. L. Leelarathna: Research Support; Current; Abbott Diabetes. Speaker's Bureau; Current; Abbott Diabetes, Insulet Corporation. Consultant; Ended; Insulet Corporation. Advisory Panel; Ended; Vertex Pharmaceuticals Incorporated.