Association between first-line monotherapy with metformin and the risk of atrial fibrillation (AMRAF) in patients with type 2 diabetes

•Diabetes increases risk of atrial fibrillation (AF)•Dipeptidyl peptidase-4 inhibitors and thiazolidinediones decrease the incidence of AF in patients with diabetes.•Metformin is the first-line medication for diabetes with proposed anti-inflammatory and cardioprotective benefits•Metformin monotherapy, compared to other non-insulin diabetes monotherapies, was not associated with decreased risk of AF.