Type 2 diabetes and the coronary angiographic state are mutually independent predictors of future vascular events among angiographied coronary patients

Background/Aims: Type 2 diabetes (T2DM) in cross-sectional studies is associated with coronary artery disease (CAD) and prospectively confers a strongly increased risk of vascular events. It is not certain to what extent the baseline CAD state accounts for the increased vascular risk of diabetic patients in prospective studies because angiography usually is not performed.

Methods: We therefore enrolled 750 consecutive patients undergoing coronary angiography for the evaluation of established or suspected stable CAD. At angiography, CAD was diagnosed in the presence of any irregularities of the vessel wall. Stenoses ≥50% were considered significant, and the extent of CAD was defined as the number of significant stenoses in a patient. Vascular events were recorded over 4 years.

Results: The prevalence of CAD (87.8% vs. 80.4%; p=0.029) and of significant stenoses (69.5% vs. 58.4%; p=0.010) as well as the extent of CAD (1.7±1.5 vs. 1.4±1.5; p=0.014) were significantly higher in patients with T2DM (n=164) than in nondiabetic subjects (n=586). Prospectively, T2DM after multivariate adjustment strongly predicted vascular events (adjusted hazard ratio (HR)=1.66 [1.15–2.39]; p=0.006). Also, the presence of CAD (HR=2.78 [1.39–5.57]; p=0.004), the presence of significant stenoses (HR=3.67 [2.30–5.85]; p<0.001) and the extent of CAD (standardized adjusted HR=1.62 [1.41–1.87]; p<0.001) significantly predicted vascular events. These angiographic characteristics still predicted vascular events after additional adjustment for T2DM (HR=2.66 [1.33–5.34]; p=0.006, 3.57 [2.24–5.70]; p<0.001, and 1.60 [1.34–1.84]; p<0.001, respectively). Conversely, T2DM remained strongly and significantly predictive of future vascular events after adjustment for the presence and extent of CAD (HR=1.50 [1.04–2.15]; p=0.029).

Conclusions: Among angiographied coronary patients, the presence and the extent of CAD are higher in patients with T2DM than in nondiabetic individuals. Prospectively, T2DM and the baseline CAD state are mutually independent predictors of future vascular events.