OBJECTIVES: In this work, we sought to describe the baseline characteristics and the management of patients with and without diabetes hospitalized with acute coronary syndromes (ACS), as well as to assess the prognostic value of diabetes status to the severity of ACS and in-hospital mortality. METHODS: A sample of six hospitals located in Greek urban and rural regions was selected and we recorded almost all admissions due to ACS, from October 2003 to September 2004. 2,172 patients were included in the study. Socio-demographic, clinical, dietary and other lifestyle characteristics was recorded. RESULTS: Approximately 1 in 3 patients admitted at the hospital with ACS had history of diabetes. Diabetes mellitus was associated with old age, female gender and more prevalent history of coronary heart disease, hypertension and renal failure. Diabetics sought medical care later and they were less likely to receive fibrinolytic therapy. No statistically significant difference was observed on severity of ACS between diabetics and nondiabetics. The in-hospital mortality was higher in diabetics compared to nondiabetics. In a multivariate analysis only insulin-treated diabetics had an increased mortality rate compared to nondiabetics. CONCLUSIONS: The use of more effective medications and interventions must be used in diabetics who develop ACS, as well as educational efforts should be directed to those patients for reducing the pre-hospital delay.