Relation of Diabetes Mellitus to Incident Dementia in Patients With Atrial Fibrillation (from the Atherosclerosis Risk in Communities Study)

The association of diabetes mellitus (DM), an established risk factor for dementia in the general population, with incident dementia in patients with atrial fibrillation (AF) has not been explored. We performed a cohort study where we identified subjects with incident AF in the Atherosclerosis Risk in Communities cohort (1987 to 2017) and determined their DM status, fasting blood glucose before AF diagnosis and hemoglobin A1c levels using information from the closest previous study visit. Incident dementia was expert adjudicated using information from cognitive assessments, informant interviews and hospitalization surveillance. We calculated hazard ratios (HRs) and 95% confidence intervals (CIs) of incident dementia for each level of exposure using Cox models and adjusting for potential confounders. We analyzed 3,020 patients with AF in the Atherosclerosis Risk in Communities cohort (808 with DM) and 530 had incident dementia after a mean follow-up of 5.3 years after AF diagnosis. After multivariable adjustment, patients with AF with prevalent DM had higher rates of dementia than those without DM, HR 1.45 (95% CI 1.16 to 1.80). A value of hemoglobin A1c ≥6.5% was associated with a HR 1.29 (95% CI 0.97 to 1.71) of dementia. However, fasting blood glucose was not associated with rates of dementia independent of DM status. In conclusion, DM was associated with higher rates of dementia in patients with AF. DM prevention and control could be a promising avenue for reducing risk of dementia in AF.