HbA1c Variability and the Risk of Dementia in Patients with Diabetes: A Meta-Analysis

Abstract

Background. Variability of HbA1c has been related to the incidence micro and macrovascular complications in patients with diabetes. However, the association between of visit-to-visit variability of HbA1c and risk of dementia has not been fully determined. A meta-analysis was performed to comprehensively evaluate the above association. Methods. Medline, Embase, and Web of Science databases were searched for longitudinal follow-up studies comparing the incidence of dementia in diabetic patients with higher or lower variability of HbA1c. A random-effect model incorporating the potential heterogeneity among the included studies were used to pool the results. Results. Five retrospective studies with 577592 diabetic patients were included, and 99% of them were with type 2 diabetes mellitus (T2DM). With a mean follow-up duration of 6.3 years, 31963 patients had newly diagnosed dementia. Pooled results showed that diabetic patients with higher HbA1c variability was associated with higher risk of dementia, as evidenced by studies with coefficient of variation (CV: hazard ratio (HR): 1.06; 95% confidence interval (CI): 1.003–1.120; $p=0.04$ ; I2 = 47%) and standard deviation (SD : HR: 1.19; 95% CI: 1.06–1.32; $p=0.002$ ; I2 = 0%) of HbA1c in continuous variables, and CV of HbA1c (HR: 1.18; 95% CI: 1.08–1.28; $p<0.001$ ; I2 = 31%) in categorized variables. Conclusions. Higher variability of HbA1c is associated with a higher incidence of dementia in patients with diabetes.