The aim of this study was to evaluate whether noninsulin-dependent diabetes (NIDDM) and its metabolic control and duration predict coronary heart disease (CHD) events during a 3.5-year follow-up in a randomly selected Finnish population sample 65-74 years of age at baseline. Of 1,298 subjects participating in the baseline study, 1,069 were nondiabetic and 229 had NIDDM. During the follow-up, 3.4% of nondiabetic and 14.8% of NIDDM subjects died from CHD or had a nonfatal myocardial infarction (MI). The impact of NIDDM on CHD mortality and morbidity was more marked in women than in men. Odds ratios (ORs) and their 95% confidence intervals for CHD death and nonfatal MI in women with NIDDM compared with women with normal glucose tolerance were 11.7 (3.8-36.4) and 4.7 (3.6-6.1). In men, the corresponding ORs were 0.43 (0.1-1.9) and 1.4 (0.6-3.2). In multiple logistic regression analyses including all study subjects, NIDDM (P < 0.01), male sex (P < 0.05), and previous MI (P < 0.01) predicted CHD death (n = 45). NIDDM (P < 0.01), male sex (P < 0.05), previous MI (P < 0.05), current smoking (P < 0.001), systolic blood pressure (P < 0.001), and low high-density lipoprotein cholesterol (P < 0.01) predicted all CHD events (CHD death or nonfatal MI) (n = 107). In NIDDM subjects, only glycated hemoglobin A1c (GHbA1c) at baseline (P < 0.01) and duration of diabetes (P < 0.05) predicted CHD death (n = 15) and all CHD events (n = 33). There was a significant increase in the risk of CHD death and all CHD events in NIDDM subjects with GHbA1c levels higher than 7.0% compared with diabetic subjects with lower GHbA1c (ORs 4.3 [1.1-16.7] and 2.2 [1.0-5.1]). In conclusion, NIDDM and its metabolic control and the duration of diabetes are important predictors of CHD in elderly subjects, particularly in women.