Glucose abnormalities detected by continuous glucose monitoring in very old adults with and without diabetes

Objective: To characterize the prevalence of CGM-defined glucose abnormalities in a large, community-based population of very old adults (>75 years). Research Design and Methods: A cross-sectional analysis of 1,150 older adults with and without diabetes who attended the Atherosclerosis Risk in Communities Study (2021-2022). Diabetes was based on a self-reported diagnosis of diabetes by a health care provider, use of diabetes medication, or an HbA1c≥6.5%. Prediabetes was defined as an HbA1c 5.7%-<6.5% and normoglycemia as an HbA1c<5.7%. We analyzed CGM metrics including mean glucose, measures of hyperglycemia and the coefficient of variation, by diabetes status. Results: Of the 1,150 participants (mean age 83 years, 59% women, 26% who are Black), 35.1% had normoglycemia, 34.5% had prediabetes and 30.4% had diabetes. The summary 24-hour ambulatory glucose profile for participants with prediabetes was very similar to those with normoglycemia. No participants with normoglycemia or prediabetes had a CGM mean glucose >140 mg/dL, while 32.7% of participants with diabetes had a CGM mean glucose >140 mg/dL. Conclusion: In very old adults with normal or prediabetic HbA1c, hyperglycemia detected by CGM was rare. This suggests that HbA1c adequately captures the burden of hyperglycemia for most people in this population.