Risk of atrial fibrillation in people with type 1 diabetes compared with matched controls from the general population: a prospective case-control study.

BACKGROUND: Type 1 diabetes is associated with an increased risk of developing several cardiovascular complications. To our knowledge, the independent association between type 1 diabetes and atrial fibrillation has not been studied.

METHODS: We did a prospective case-control study of individuals with type 1 diabetes in the Swedish National Diabetes Registry who were each matched with five controls for age, sex, and county of residence who were randomly selected from the Swedish Population Register. Cases of atrial fibrillation were obtained from the Swedish National Patient Registry.

FINDINGS: We followed up 36 258 patients with type 1 diabetes and 179 980 controls between Jan 1, 2001, and Dec 31, 2013. Median follow-up was 9·7 years (IQR 5·2-13·0) for patients and 10·2 years (5·7-13·0) for controls. 749 (2%) individuals with type 1 diabetes and 2882 (2%) controls were diagnosed with atrial fibrillation, with an adjusted hazard ratio (HR) of 1·13 (95% CI 1·01-1·25; p=0·029) in men and 1·50 (1·30-1·72; p<0·0001) in women (p=0·0019 for interaction). The excess risk of atrial fibrillation in individuals with type 1 diabetes increased with worsening glycaemic control and renal complications. Among individuals with normoalbuminuria, no excess risk of atrial fibrillation was noted in men with type 1 diabetes who had HbA1c lower than 9·7% (<83 mmol/mol) or in women with type 1 diabetes who had HbA1c lower than 8·8% (<73 mmol/mol).

INTERPRETATION: Compared with the general population, the risk of atrial fibrillation in men with type 1 diabetes was slightly raised, whereas for female patients it was 50% higher. The risk of atrial fibrillation in people with type 1 diabetes increased with renal complications and poor glycaemic control.

FUNDING: Novo Nordisk Foundation, Swedish State (ALF agreement), Swedish Research Council (SIMSAM), Swedish Heart and Lung Foundation, Swedish Diabetes Foundation, Diabetes Wellness.