Glycemic Control, Diabetic Complications, and Risk of Dementia in Patients With Diabetes: Results From a Large U.K. Cohort Study

Objective: Type 2 diabetes is an established risk factor for dementia. However, the roles of glycaemic control and diabetic complications in the development of dementia have been less well substantiated. This large-scale cohort study aims to examine associations of longitudinal HbA1c levels and diabetic complications with the risk of dementia incidence among patients with type 2 diabetes.

Research Design and Methods: Data of eligible diabetes patients, aged over 50 years in the UK Clinical Practice Research Datalink from 1987 to 2018, were analysed. Time-varying Cox regressions were used to estimate adjusted hazard ratios (HR) and 95% confidence intervals (CI) for dementia risk.

Results: Among 457,902 diabetes patients, 28,627 (6.3%) incident dementia cases were observed during a median of six years follow-up. Patients with recorded hypoglycaemic events or microvascular complications were at higher risk of dementia incidence compared to those without such complications (HR [95% CI]=1.30 [1.22-1.39] and 1.10 [1.06-1.14], respectively). The HbA1c level, modelled as a time-varying exposure, was associated with increased dementia risk (HR=1.08, 95% CI: 1.07-1.09 per 1% HbA1c increment) among 372,287 diabetes patients with post-diagnosis HbA1c records. Similarly, higher coefficient of variation of HbA1c during the initial three years of follow-up was associated with higher subsequent dementia risk (HR=1.03, 95% CI: 1.01-1.04 per 1 SD increment).

Conclusions: Higher or unstable HbA1c levels and the presence of diabetic complications in patients with type 2 diabetes are associated with increased dementia risk. Effective management of glycaemia might have significant role in maintaining cognitive health among older adults with diabetes.