Associations of Mid- and Late-Life Fasting Blood Glucose Levels With Dementia Risk Among Patients With Diabetes: Framingham Heart Study

BackgroundDiabetes is an established risk factor for dementia. However, the association has been less consistent at the population level and may vary over the lifespan. The impacts may be influenced by glucose fluctuation over lifetime.MethodsWe used data from the Framingham Offspring cohort to evaluate the dementia risk associated with fasting blood glucose (FBG) across age ranges. Cox proportional hazards regression models were fitted to investigate the association of diabetes status at each examination with dementia risk, and the associations between FBG levels and dementia across age spans. Group-based trajectory models were used to create FBG trajectories from mid to late-life for comparison.ResultsHigher FBG level at midlife was not associated with an increased risk of dementia. For participants with diabetes, higher FBG at age 60 and 70 years was associated with subsequent dementia (HR: 1.72, 95% CI: 1.07-2.75; HR: 1.91, 95% CI: 1.24-2.91). Diabetic participants with first midlife increasing and then late-life declining patterns of FBG were at greater increased risk of dementia compared to participant without diabetes. (HR: 2.00, 95% CI: 1.04-3.85).ConclusionThe relationship between FBG and dementia risk was heterogeneous across the adult age range. Diabetes at midlife is a risk factor for dementia, but high glucose levels at 60-70 years followed by a decline suggests that less controlled diabetes during high age risk for dementia onset may represent another prodromal risk factor and presymptomatic metabolic indicator of dementia.