Epidemiological studies have reported that patients with type 2 diabetes mellitus (DM) have increased mortality and morbidity from cardiovascular diseases, independent of other risk factors. However, most of these studies have been performed in selected patient groups. The purpose of the present study was prospectively to assess the impact of type 2 DM on cardiovascular morbidity and mortality in an unselected population. A total of 13,105 subjects from the Copenhagen City Heart Study were followed up prospectively for 20 years. Adjusted relative risks of first, incident, admission for, or death from ischemic heart disease, acute myocardial infarction, or stroke, as well as total mortality in persons with type 2 DM compared with healthy controls, were estimated. The relative risk of first, incident, and admission for myocardial infarction was increased 1.5- to 4.5-fold in women and 1.5- to 2-fold in men, with a significant difference between sexes. The relative risk of first, incident, and admission for stroke was increased 2- to 6.5-fold in women and 1.5- to 2-fold in men, with a significant difference between sexes. In both women and men the relative risk of death was increased 1.5 to 2 times. In persons with type 2 DM, the risk of having an incident myocardial infarction or stroke is increased 2- to 3-fold and the risk of death is increased 2-fold, independent of other known risk factors for cardiovascular diseases.