There is scarce information available about the outcome of diabetic patients with acute myocardial infarction (AMI) treated with percutaneous transluminal coronary angioplasty (PTCA). We sought to compare left ventricular (LV) function, and angiographic and clinical outcomes in diabetics versus nondiabetics with AMI treated with primary PTCA. This study examined 720 consecutive patients with AMI treated with primary PTCA, 102 of whom had diabetes. Six-month follow-up coronary angiography was obtained in 560 patients (88% of eligible patients). In a subgroup of 284 patients, LV function was serially determined by 2-dimensional echocardiography. During 6-month follow-up no significant differences were observed between diabetics and nondiabetics with regard to restenosis rates (31.6% vs 28.2%, p = 0.6), recovery of LV function (6-month wall motion score index: 1.8 +/- 0.7 vs 1.8 +/- 0.7, p = 0.88; 6-month LV ejection fraction: 48.5 +/- 12% vs 51.2 +/- 13%, p = 0.173), nonfatal re-AMI rates (2.9% vs 1.3%, p = 0.2), and target vessel revascularization rates (21.6% vs 16.8%, p = 0.2). Early and late mortality were higher in diabetics than in nondiabetic patients (8.8% vs 4.2%, p = 0.045 and 11.7% vs 5.5%, p = 0.016, respectively). By Cox analysis, diabetes was an independent predictor of both early (odds ratio [OR] 2.4, 95% confidence interval [CI] 1.1 to 5.3, p = 0.03) and late mortality (OR 2.37, 95% CI 1.16 to 4.84, p = 0.017) as well as 6-month major adverse cardiac events (MACEs): death, re-AMI, target vessel revascularization (OR 1.51, 95% CI 1.04 to 2.18, p = 0.03). Thus, diabetes is an independent predictor of clinical outcome even if PTCA is used as the primary reperfusion strategy.