Type 1 versus type 2 diabetes and thromboembolic risk in patients with atrial fibrillation: a nationwide cohort study

BACKGROUND: Atrial fibrillation is a common cause of stroke, and diabetes increases stroke risk. Stroke risk may vary depending on the type of diabetes. We investigated whether type 1 and type 2 diabetes are associated with different risks of thromboembolism among patients with atrial fibrillation.

METHODS: We used data from Danish nationwide registries to identify patients with a prior diagnosis of diabetes and an incident nonvalvular atrial fibrillation diagnosis in the period of January 1, 2005 to December 31, 2015. Cox regression analysis was used to estimate hazard ratios (HR) for the outcome thromboembolism.

RESULTS: The study population included 10,058 patients with a prior diagnosis of diabetes and an incident diagnosis of atrial fibrillation. At three-year follow-up, type 2 diabetes was not associated with a higher risk of thromboembolism compared to type 1 diabetes, with an adjusted HR of 1.15 (95% CI: 0.91-1.44). In an age-stratified analysis, patients aged below 65 years of age had an adjusted HR of 1.97 (95% CI: 1.07-3.61), whereas patients aged 65-74 years or ≥75 years had adjusted HRs of 0.99 (95% CI: 0.67-1.46) and 1.10 (95% CI: 0.80-1.51), respectively.

CONCLUSION: We found no overall credible association between the type of diabetes and risk of thromboembolism in this cohort of non-anticoagulated patients with incident atrial fibrillation. Nonetheless, the subset of patients aged below 65 years of age displayed a higher risk of thromboembolism among patients with type 2 diabetes as compared to patients with type 1 diabetes.