Summary 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. [Diabetologia (1997) 40: 824–829]