BACKGROUND: American and European consensus opinions recommend that diabetes mellitus be regarded as a ‚coronary risk equivalent‘, that is, as conferring the same risk of myocardial infarction as established coronary heart disease. We examined if this holds true for men in the Prospective Cardiovascular Münster Study (PROCAM). DESIGN: We conducted a single-centre, prospective, epidemiological study, calculating risk using the PROCAM calculator, which takes diabetes mellitus into account, in men at work in public authorities and large companies in the region of Münster, Germany. PARTICIPANTS: Five thousand, three hundred and eighty-nine men aged 35-65 years at recruitment participated, 3778 of whom were normoglycaemic, 1205 of whom displayed impaired fasting glycaemia, and 406 of whom suffered from diabetes mellitus. Coronary events (fatal or nonfatal myocardial infarction, sudden coronary death) occurring within 10 years of unbroken follow-up were assessed. RESULTS: Of men with diabetes mellitus 13.3% suffered a coronary event within 10 years, compared with 7.3% of men with impaired fasting glycaemia, and 5.3% of normoglycaemic men. Using the PROCAM risk calculator, only 26.5% of the men with diabetes mellitus were calculated to have a 10-year coronary event risk at or above the threshold of 20% (high risk) regarded as being equivalent to the risk conferred by established coronary heart disease. Eight percent of men with impaired fasting glycaemia and 5.5% of normoglycaemic men were at high risk. The positive predictive value of a high-risk estimate was 35% in men with diabetes, 32% in men with impaired fasting glycaemia, and 31% in normoglycaemic men. CONCLUSION: In PROCAM, less than a third of men with diabetes were classified as being at high risk of coronary events. It is therefore incorrect to regard the presence of diabetes mellitus as a coronary risk equivalent.