Insulin-Treated Versus Noninsulin-Treated Diabetes And Risk Of Ischemic Stroke In Patients With Atrial Fibrillation

Background: Diabetes mellitus (DM) and atrial fibrillation (AF) are known risk factors for ischemic stroke. Recent data, however, suggest that only insulin-treated DM is a risk factor for ischemic stroke among AF patients.Objectives: To evaluate the risk of stroke in patients with insulin and noninsulin treated DM.Methods: We included AF patients undergoing coronary angiography in Western Denmark between 2003 and 2016. Patients were categorized as 1) insulin treated DM, 2) noninsulin treated DM, or 3) nonDM patients. The main outcome was ischemic stroke >30 days after CAG.Results: AF patients (n = 21,223) were included, of whom 17,181 (81%) did not have DM, 2890 (14%) had noninsulin-treated DM and 1152 (5%) had insulin-treated DM. Median follow-up was 5.3 years. Ischemic stroke rates were 0.83 per 100 person-years for nonDM, 1.19 for noninsulin-treated DM and 1.40 for insulin-treated DM. Insulin-treated DM (adjusted hazard ratio (HRadj) 1.48, 95% CI 1.15-1.91) and noninsulin-treated DM patients (HRadj 1.30, 95% CI 1.09-1.54) had higher risks of ischemic stroke than nonDM patients. There was no difference between insulin-treated DM and noninsulin-treated DM (HRadj 1.09, 95% CI 0.82-1.46). Stratification by coronary artery disease yielded comparable risk estimates.Conclusion: In patients with AF, DM increases the risk of ischemic stroke, regardless of treatment.