Risk of stroke and mortality in patients with atrial fibrillation and insulin dependent versus non-insulin dependent diabetes mellitus

Background: Diabetes mellitus (DM) is a known risk factor for thromboembolic events in patients with non-valvular atrial fibrillation (NVAF). Whether patients on insulin therapy are at an increased risk for stroke compered to patients solely oral antidiabetic treatment is not yet established.

Aim: To assess the risk of ischemic stroke and mortality in patients with NVAF and DM treated by insulin vs. oral antidiabetic treatment.

Methods: A prospective, historical cohort study based on the Clalit Health Services electronic database, including 12,231 individuals age ≥ 21 years with a first diagnosis of NVAF between 1/2010 to 12/2016 which also have DM and have follow-up period of at least1 year. Patients were divided into two groups based on their diabetes therapy regiment (insulin vs. oral medications).

Results: Of the 12,231 patients included into the study 3510 (28.7%) had an insulin-requiring diabetes. The median age was 72.4 years (IQR 65-80) in the insulin-treated group and 75.2 (IQR 68-83) in the orally treated group, with a slight majority of women in both groups, 51.6% and 53.5% respectively. The incidence of stroke was 2.62 per 100 person-years in the insulin group and 2.02 in the oral-treated group. Although patients on insulin had a significantly increased risk for stroke compare to orally treated patients in the univariate analysis (HR:1.34; 95%CI:1.13-1.60), in the adjusted model this association was insignificant (HR:1.17; 95%CI:0.96-1.41). The rate of mortality per 100 person-years was 19 in the insulin-treated group and 12.6 in the oral-treated group. The on-insulin-group had a significantly higher mortality risk compared to the non-insulin group (HR:1.38; 95%CI:1.29-1.48), as found in the multivariate Cox model,

Conclusion: In this cohort of patients with NVAF and DM, patients on-insulin are at increased risk of all-cause mortality and have a trend of increased risk for stroke compered to patient on oral-antidiabetic medications.