In order to determine the effect of diabetes on the mortality rate and mode of death during 5 years of follow-up among patients who came to the emergency department with acute chest pain or other symptoms suggestive of acute myocardial infarction (AMI), all patients thus presenting to one single hospital during a period of 21 months were followed for 5 years. In total 5230 patients were included, of whom 402 (8%) had a history of diabetes. Patients with diabetes differed from those without by being older, having a higher prevalence of previously diagnosed cardiovascular diseases, having less symptoms of chest pain and more symptoms of acute severe heart failure, and more electrocardiographic (ECG) abnormalities on admission. Diabetic patients had a 5-year mortality of 53.5% as compared with 23.3% among non-diabetic patients (p < 0.001; adjusted risk ratio 1.60; 95% confidence limits 1.35-1.90). Among diabetic patients the following appeared as independent predictors of death: age (p < 0.001), ST-segment elevation on admission (P < 0.001), a history of myocardial infarction (p < 0.05), and a non-pathological ECG on admission (p < 0.001). We conclude that among diabetic patients admitted to the emergency department with acute chest pain or other symptoms suggestive of AMI more than 50% are dead 5 years later. Future research should focus on interventions in order to reduce their mortality.