Usefulness of CGM Metrics to Assess Glycemic Control in Non-White Subjects with Diabetes

Introduction: Glucose management indicator (GMI), a CGM-based metric, of mean glucose is thought to give more information on glycemic excursion than laboratory measured A1c. We have shown differences in relationship between A1c and GMI in different age groups, however it is not known whether racial differences affect the relationship between A1c and GMI. Methods: We analyzed data from patients with diabetes undergoing professional CGM (proCGM) at a tertiary care diabetes center between year 2017 and 2020, who had at least 10 days of CGM data. Medical records were queried to obtain demographic information and laboratory A1c results from within 1 month of CGM wear. GMI was calculated as Formula =3.31 + (0.02392 × mean glucose in mg/dL). Results: We evaluated 316 patients (mean age 60 ±18, 51% female, duration of diabetes 24±15 years, T1D 45% and T2D 55%, 78% white and 22% non-white). Subjects were identified by race as non-white (T1D 22%; T2D 78%) or white (T1D 45%; T2D 55%). CGM metrics in the non-white and white cohort were similar; time in range (728 ± 342 vs. 722 ± 307 min/day; p=ns), time <70 mg/dL (90 ± 98 vs. 97 ± 108 min/day; p=ns ), and time >180 mg/dL (568 ± 324 vs. 569 ± 346 min/day; p=ns). While GMI was not different in the nonwhite vs. white cohort (7.6 ± 1.3 vs. 7.7 ± 1.5; p=ns), A1c was higher in non-whites (8.7 ± 1.6 vs. 8.1 ±1.3; p=0.004). An absolute difference between A1c and GMI was higher in nonwhite vs. white (1.5 ± 0.88 vs. 1.1 ± 0.82 vs; p=0.006) and the absolute difference of 0.5% was observed in higher proportion of nonwhite patients (50 [75%] vs. 165 [68%]). Conclusions: In our study cohort, the relationship between GMI and A1c is different in non-white versus white population despite similar CGM metrics. This difference might be important to consider when assessing glycemic control and goals in diverse patient population. Disclosure E. Toschi: Consultant; Self; Medtronic. C. Slyne: None. A. Michals: None. K. Sifre: None. R. Dewar: None. A. Atakov-castillo: None. D. J. Davis: None. M. Munshi: Consultant; Self; Sanofi. Funding National Institutes of Health (1DP3DK112214-01)