The impact of glucose tolerance on the incidence of ischemic heart disease (IHD), cerebrovascular disease (CVA), and peripheral arterial disease (PAD) was investigated in the Zutphen Study. In 1970 a complete oral glucose tolerance test (GTT) was carried out on 400 normoglycemic men aged 50-70 yr. A morbidity follow-up was completed in 1985. With GTT classified as the dichotomous variable using the median value of the area under the curve, elevated risks for IHD (RR = 1.6, p < 0.05), fatal IHD (RR = 2.3, p < 0.01), and CVA (RR = 1.9, p < 0.10) were observed, adjusted for potential confounders. No association with PAD was found. Also the risk among non-insulin-dependent diabetics (n = 46) was assessed. These men were clinically diagnosed between 1960 and 1985, median year of diagnosis being 1973, at age 61 yr. Compared with 230 matched non-diabetics increased risks were observed for fatal IHD (p = 0.05), CVA (p = 0.10) as well as PAD (p = 0.05). Thus an elevated risk for IHD, and possibly CVA, may have been found with lower levels of glucose than assumed previously, suggesting a continuous risk gradient. For PAD the relations with glucose tolerance are more complex.