['Diabetic patients tend to have more extensive and diffuse coronary artery disease (CAD) that may contribute to the less favorable outcomes in them. The aim of this study was to elucidate the predictors of the angiographic severity and extent of CAD in patients with diabetes.', 'A total of 203 diabetic patients (116 men; mean age, 61.9+/-10.8) who were referred for a first coronary angiogram were included. The extent and severity of CAD was assessed in several ways. The first was a simple classification in one-vessel, two-vessel, and three-vessel disease scoring system. The total numbers of segments with > or = 20 and > or = 50% stenosis were calculated as CASS 20 and CASS 50 scores, respectively. Hamsten and Gensini scores were also calculated.', 'Of the 203 patients included in the study, 175 (86.2%) had CAD. Multivariate ordinal logistic regression analysis showed that age (Wald 5.741, P=0.017), glomerular filtration rate (Wald 5.032, P=0.025), previous myocardial infarction (Wald 10.955, P=0.001), and family history of CAD (Wald 7.236, P=0.007) were independent predictors of the severity of CAD, as assessed by the clinical zero-vessel to three-vessel disease scoring system. On stepwise multiple linear regression analysis, glomerular filtration rate was an independent predictor of the CASS 20 (r=-0.221, P=0.004), CASS 50 (r=-0.239, P=0.005), Gensini (r=-0.328, P<0.001), and Hamsten (r=-0.320, P<0.001) scores. Previous myocardial infarction was an independent predictor of the CASS 50 (r=0.355, P<0.001), Gensini (r=0.350, P<0.001), and Hamsten (0.256, P<0.001) scores. Age and sex were independent predictors for the CASS 50 (r=0.174, P=0.039; r=0.172, P=0.016, respectively) and Hamsten (r=0.212, P=0.011; r=0.244, P=0.001, respectively) scores.'] Is renal dysfunction the most important predictor of the extent and severity of coronary artery disease in patients with diabetes mellitus?