OBJECTIVE To compare the outcome of acute myocardial infarction in NIDDM patients and nondiabetic control subjects. The relation of glycemic control, duration of diabetes, and major diabetic complications to the outcome of acute myocardial infarction in diabetic subjects was investigated. RESEARCH DESIGN AND METHODS This was a prospective, hospital-based, case-control study. RESULTS One hundred and ninety-six NIDDM patients and 196 nondiabetic control subjects with acute myocardial infarction were entered into the study. 23.5% of diabetic subjects and 34.2% of control subjects received thrombolytic therapy (P < 0.05). Diabetic subjects showed signs of reperfusion less often than control subjects (P < 0.05). Mortality was higher in the diabetic group (17.3 vs. 10.2%, P < 0.05). Pump failure (38.3 vs. 16.8%, P < 0.01) and cardiogenic shock (9.7 vs. 3.6%, P < 0.05) also occurred more frequently in diabetic subjects. Loss of heart rate variability was correlated with both pump failure and mortality; proliferative retinopathy was correlated with pump failure. Glycemic control and other diabetic complications did not correlate with outcome. CONCLUSIONS Our findings confirm the higher mortality and incidence of pump failure in acute myocardial infarction with co-morbid diabetes. They suggest that the less frequent use of thrombolytic therapy, lower reperfusion rates, and more advanced coronary artery disease might be contributory. The presence of autonomic neuropathy and microvascular disease probably also contribute to poor outcome; other major diabetic complications and diabetic control did not influence outcome.