ADA Standards of Medical Care considers 14-day CGM-based GMI an A1c surrogate for clinical management. To date, supporting evidence is from T1D or insulin-treated T2D populations. As CGM demand and access grows, quantifying A1c-GMI discordance in diverse T2D populations can inform practice. We evaluated this discordance, stratified by T2D drugs and A1c. CGM-wearing adults with T2D, an overlapping A1c and GMI date (10/2019 to 3/2022), and CGM data sufficiency (DS) ≥ 70% were included. Prior 3 month pharmacy claims defined drug histories. We calculated the Pearson correlation coefficient (r) and A1c-GMI differences by subgroup. A1c-GMI pairs existed for 2,760 people (mean [SD] age 55 [9]; 46% F; 58% had A1c <7%). Overall, pairs highly correlated (56% differed by <0.5%; r=0.80). Non-insulin T2D drug users (N=1,674) had slightly higher concordance than basal insulin (N=437) and basal-bolus insulin users (N=317), with 58%, 50%, and 56% discordance <0.5% (r=0.79, 0.77, 0.77). On average, A1c underestimated GMI for non-insulin users and overestimated GMI for basal and basal-bolus insulin users. Concordance decreased at A1c extremes, with 61-76% concordance for A1cs from 5.7% to 8%. Sensitivity analyes with lower DS had similar results. A1c-GMI discordance varied by T2D drug class and A1c, highlighting how CGM-derived measures can provide personalized insights for diverse T2D populations.
A.Jhuang: Employee; UnitedHealth Group, Stock/Shareholder; UnitedHealth Group. S.Bacon: Employee; Optum Labs, Research Support; Level2. S.Kamrudin: Employee; UnitedHealth Group. N.Thompson: Employee; Level2, Stock/Shareholder; UnitedHealth Group. C.Clark: Employee; UnitedHealth Group, Stock/Shareholder; UnitedHealth Group.
