Continuous Glucose Monitoring Measures Impact Cognitive Function in Long-Duration Type 1 Diabetes

As people with type 1 diabetes (T1D) live longer, they are increasingly presented with greater health risks tied to aging-related cognitive decline. We previously reported that participants of the Joslin 50-year Medalist Study (“Medalists”) , with T1D ≥50 years, have impaired cognitive function compared to controls without diabetes, and similar to those with type 2 diabetes. While glycemic control has been shown to impact cognitive function, the impact of day-to-day continuous glucose monitoring (CGM) measures is unclear. CGM provides measures of glycemic variability uncaptured by HbA1c alone. A 2-week block of CGM data was procured from a subset of Medalists (n=64) who also had undergone a cognitive battery testing psychomotor function (Grooved Pegboard) , verbal learning and memory (RAVLT- immediate and delayed recall) , working memory (Wechsler) and executive function (WASI) . In a cross-sectional study, log-transformed CGM metrics were tested for associations with cognitive domains in linear regression models adjusted for duration of diabetes, education status and sex. Better psychomotor function was associated with a higher time in range 70 - 180 mg/dL (p=0.04) , and with lower: glucose coefficient of variation (p=0.02) , time above range (TAR) >180 -250 mg/dL (p=0.01) , TAR > 250 mg/dL (p=0.07) , mean glucose (p=0.07) and glucose management indicator (p=0.07) . Better delayed recall associated with lower time below range < 70 mg/dL (p=0.02) and better immediate recall with lower TAR > 180 -250 mg/dl (p=0.08) . Lower HbA1c previously associated with better executive function in the Medalists, but not with other cognitive domains. This CGM study shows that glucose variability and hyperglycemia impact psychomotor function, while hypoglycemia impacts verbal learning and memory. Thus, better day-to-day glucose management in conjunction with long-term HbA1c control, are potentially important to prevent cognitive decline in aging populations with long-duration T1D. Disclosure H.Shah: None. M.Yu: None. T.Boumenna: None. J.Gauthier: None. R.Tham: None. A.Adam: None. G.L.King: Advisory Panel; Medtronic, Research Support; Janssen Pharmaceuticals, Inc. Funding Beatson Foundation