OBJECTIVE To determine whether the prognostic value of dobutamine stress echocardiography (DSE) performed early after acute myocardial infarction (AMI) is as high in diabetic patients as in nondiabetic patients. METHODS Inception cohort study. METHODS Tertiary cardiac referral center. METHODS Three hundred thirty-eight patients (116 diabetic and 222 nondiabetic) who underwent DSE after AMI were followed up for cardiac events. RESULTS Outcome events were as follows: "hard" events consisted of cardiac death and nonfatal reinfarction, while "all events" included hard events and unstable angina. The mean follow-up duration was 21 +/- 9 months. DSE results were positive in 69 diabetic patients (59.5%) and 129 nondiabetic patients (58.1%; p = 0.817). During the follow-up period, there were 25 cardiac deaths, 16 cases of nonfatal reinfarction, and 55 cases of unstable angina. The Kaplan-Meier life table showed that a positive DSE result was associated with a lower event-free survival rate in nondiabetic but not in diabetic patients in terms of hard and all events. By multivariate analysis, a positive DSE result was the strongest independent predictor of future cardiac events in nondiabetic patients. However, in diabetics, a shorter dobutamine time, rather than a positive DSE result, independently predicted cardiac events. CONCLUSIONS Our preliminary data suggest that different DSE variables should be considered when assessing the likelihood of future events in diabetic and nondiabetic patients after AMI. The observation of shorter dobutamine time, instead of DSE positivity, has a higher prognostic value in diabetics. In diabetic patients, the only significant role of DSE positivity is for predicting future unstable angina; however, its predictive value is not as good as in nondiabetic patients.