Type 2 diabetes and the risk of cardiovascular events in peripheral artery disease versus coronary artery disease

INTRODUCTION: The prevalence of type 2 diabetes mellitus (T2DM) is higher in peripheral artery disease (PAD) than in coronary artery disease (CAD) patients, and PAD overall confers higher cardiovascular risk than CAD. How cardiovascular risk compares between PAD and CAD patients when analyses are stratified by the presence of type 2 diabetes is unclear and is addressed in the present study. RESEARCH DESIGN AND METHODS: We prospectively recorded major cardiovascular events (MACE; ie, cardiovascular death, myocardial infarction or stroke) over 10.0±4.7 years in 923 patients with stable CAD, of whom 26.7% had T2DM and in 292 patients with PAD, of whom 42.1% had T2DM. Four groups were analyzed: CAD patients without diabetes (CAD/T2DM-; n=677), CAD patients with T2DM (CAD/T2DM+; n=246), PAD patients without diabetes (PAD/T2DM-; n=169) and PAD patients with T2DM (PAD/T2DM+; n=123). RESULTS: The event rate for MACE increased over our four investigated groups: it was lowest in CAD/T2DM- patients (2.52 events per 100 person-years). It was significantly higher in CAD/T2DM+ patients (3.96 events per 100 person-years; p<0.001), in PAD/T2DM- patients (3.68 events per 100 person-years; p=0.022), and in PAD/T2DM+ patients (7.10 events per 100 person-years; p<0.001), who in turn were at a higher risk than CAD/T2DM+ or PAD/T2DM- patients (p=0.001 and p<0.001, respectively). Cox regression analysis after multivariate adjustment showed that the presence of T2DM (HR=1.44 (95% CI 1.09 to 1.92); p=0.012) and the presence of PAD versus CAD (HR=1.48 (95% CI 1.15 to 1.91); p=0.002) were mutually independent predictors of cardiovascular events. CONCLUSIONS: In conclusion, our data show that T2DM as well as the presence of PAD versus CAD are mutually independent predictors of MACE. Patients with both PAD and T2DM are at an exceedingly high risk of cardiovascular events.