With the increasing use of continuous glucose monitoring (CGM), it is now known that A1c derived from venous blood often poorly correlates with estimated A1c derived from CGM. Recently, a new formula was developed, termed Glucose Management Indicator (GMI), for connecting CGM metrics to venous A1c. However, there is no data on this new measure in older population with type 1 diabetes (T1D).

Methods: We analyzed data from older adults (age ≥65 years) with T1D with stable health and medications within past 3 months. We used A1c value from venous blood, and CGM data over a 14-day period performed concurrently. We calculated GMI based on the published data by Bergenstal et al (Diabetes Care 2018) and showed the degree to which GMI and A1C agree in our older cohort versus their historical cohort.

Results: We evaluated 76 participants mean age of 71 years. As shown in the Table, in both the historical and older cohort, GMI and A1c values are identical in 19% and 17% of the time, respectively. However, the percentage of absolute values between GMI and A1c differ by ≥0.6% in 19% of the historical cohort and 33% of the older cohort. These values differ by an entire 1% in only 3% of the historical cohort while 16% of the older cohort.

Conclusions: Compared to the historical cohort, greater difference between A1C and GMI values might be more common in older adults with T1D. Larger studies are needed to understand the use of new metrics in the older population.


E. Toschi: Advisory Panel; Self; Lexicon Pharmaceuticals, Inc. C. Slyne: None. A. Atakov-Castillo: None. J. Greenberg: None. K. Sifre: None. S. Carl: None. A.B. Dufour: None. M. Munshi: Consultant; Self; Lilly Diabetes, Sanofi.


National Institute of Diabetes and Digestive and Kidney Diseases

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