Type 2 diabetes mellitus and risk of incident atrial fibrillation in women.

OBJECTIVES The purpose of this study was to assess whether changes of major atrial fibrillation (AF) risk factors and/or intercurrent cardiovascular events could explain the relationship between type 2 diabetes mellitus (T2D) and incident AF. BACKGROUND Previous studies found an increased risk of incident AF among individuals with T2D, but few, if any, of these studies took into account changes of AF risk factors over time. METHODS A total of 34,720 female health professionals who participated in the Women's Health Study, and who were free of cardiovascular disease and AF at baseline were followed for a median of 16.4 years. Cox proportional-hazards models were constructed to assess the relationship between T2D and incident AF, using either information at baseline or time-varying covariates for both T2D and potential confounders. RESULTS At baseline, 937 (2.7 %) women had T2D. Compared with women without T2D, women with T2D had an age-adjusted hazard ratio (HR) for new-onset AF of 1.95 (95% confidence interval [CI]: 1.49 to 2.56; p<0.0001). In multivariable analyses adjusting for baseline confounders, this HR was substantially attenuated, but baseline T2D remained a significant predictor of incident AF (HR: 1.37, 95% CI: 1.03 to 1.83; p=0.03). In time-updated models that adjusted for changes in AF risk factors and intercurrent cardiovascular events, the HR for T2D was attenuated further and became nonsignificant (HR: 1.14; 95% CI: 0.93 to 1.40; p=0.20). CONCLUSIONS Although this study confirms a significant relationship between baseline T2D and incident AF, our data suggest that the increased risk associated with T2D is mainly mediated by changes of other AF risk factors.