The prevalence of coronary heart disease was studied in 1984-1988 in 1,092 individuals with normal glucose tolerance, 173 individuals with impaired glucose tolerance, and 429 individuals with non-insulin-dependent diabetes mellitus, who were age 25-74 years and were from a biethnic community in the San Luis Valley, Colorado. Glucose tolerance was classified using the World Health Organization criteria, and coronary heart disease prevalence was assessed using the Rose Questionnaire and a resting electrocardiogram. Compared with normal glucose tolerance, coronary heart disease was significantly more prevalent in diabetic non-Hispanic white women (odds ratio (OR) for all end points combined = 3.2, 95% confidence interval (Cl) 1.8-5.5) and men (OR = 1.9, 95% Cl 1.1-3.3) and in diabetic Hispanic women (OR = 1.7, 95% Cl 1.1-2.5), but not men (OR = 1.0, 95% Cl 0.6-1.7). Among diabetic men, the prevalence of possible myocardial infarction was lower in Hispanics than in non-Hispanic whites (OR = 0.4, 95% Cl 0.2-0.7). Similar patterns of coronary heart disease were observed in individuals with impaired glucose tolerance. The paradoxically low prevalence of coronary heart disease in Hispanics with non-insulin-dependent diabetes mellitus, especially men, may be due to unknown protective factors, increased case fatality, or competing mortality in this group.