The adoption of Western lifestyles is known to lead to increasing prevalence of non-insulin-dependent diabetes mellitus in Africa, yet epidemiological studies using standardised methods are rare. The prevalence of diabetes and impaired glucose tolerance was determined in a rural and an urban community in Cameroon using the 75-g oral glucose tolerance test and the World Health Organization diagnostic criteria in 719 rural (292 men, 427 women) and 1048 urban (458 men, 590 women) subjects aged 24-74 years. The response rate was 95 and 91% for the rural and urban population, respectively. The age-standardized prevalence of diabetes in the rural and urban population was respectively 0.9% (95% confidence interval (0.2-2.7)) and 0.8% (0.2-1.8) for men and 0.5% (0.1-1.6) and 1.6% (0.7-3.1) for women, and that of impaired glucose tolerance was 5.8% (3.3-9.4) and 1.8% (0.9-3.2) for men, and for women, 2.2% (1.0-4.0) and 2.0% (0.6-4.5). Although for both men and women the body mass index was higher at all ages in the urban than in the rural area, the 2-h plasma glucose, even after adjustment for age and body mass index, was significantly higher in the rural than in the urban area (p < 0.005, p < 0.002 for men and women, respectively). There was a female excess of diabetes in the urban area and an equal sex distribution in the rural area. In the rural area 67% (4 of 6) of diabetic subjects were unknown before the survey, compared with 57% (8 of 14) in the urban area. These data indicate a low prevalence of diabetes in Cameroon; however, the prevalence of impaired glucose tolerance suggests an early stage of a diabetes epidemic.