Abstract Body (Do not enter title and authors here): Type 2 Diabetes (T2DM) and pre-existing coronary artery disease (CAD) are strong and independent risk factors for cardiovascular events, and data from large cohort studies suggest that the cardiovascular risk conferred by T2DM in the absence of CAD is equivalent to that conferred by CAD in the absence of T2DM. However, because the presence of CAD in these studies was defined clinically rather than by visualization, unrecognized subclinical CAD in T2DM patients may have biased results.
We therefore prospectively investigated patients with T2DM and non-diabetic subjects in whom the baseline CAD state was diagnosed angiographically. We recorded cardiovascular events over a follow-up period of 22 years in a large cohort of 1819 patients undergoing coronary angiography for the evaluation of established or suspected stable CAD.
From our patients, 595 had neither significant CAD nor T2DM (CAD-/T2DM-), 171 had T2DM but not significant CAD (CAD-/T2DM+), 701 had significant CAD but not T2DM (CAD+/T2DM-) and 352 had both T2DM and significant CAD (CAD+/T2DM+). The incidence of cardiovascular events was lowest in CAD-/T2DM- patients (24.7%). Compared to this group it was significantly higher in CAD-/T2DM+ patients (36.1%; p<0.001) and in CAD+/T2DM- patients (50.8%; p<0.001) and highest (p=0.001) in CAD+/T2DM+ patients, in whom it was higher than in CAD-/T2DM+ (p<0.001) or CAD+/T2DM- (p=0.001) patients. Importantly, CAD+/T2DM- patients were at a significantly higher risk of cardiovascular events than CAD-/T2DM+ patients (p<0.001). In Cox regression analysis the risk increase conferred by CAD was higher (adjusted (HR 2.35 [1.92-2.89]; p<0.001) than that conferred by T2DM (adjusted HR 1.54 [1.33-1.78]; p< 0.001).
From our long term results we conclude that angiographically diagnosed CAD is a stronger predictor of future cardiovascular events than T2DM. T2DM is not a CAD risk equivalent.