1028 (99%) of the 1038 inhabitants of the West African village of Agbave and a random sample of 353 (12·4%) of the population of 2850 in Kati, another West African village, were screened for diabetes. Also recorded were their anthropometric data, dietary habits, possession of antibodies to malaria, and serum IgG concentrations. About 85% of the study population consumed cassava root at least once a day. The mean (SD) capillary random blood glucose concentration was 5·1 (1·1) mmol/l in men and 5·1 (0·6) in women. The mean (SD) body mass index was 20·2 (1·8) in men and 20·7 (2·3) in women. The mean blood glucose was similar whether cassava was consumed once daily, more than once daily, or less than once daily. None of the 1381 subjects examined had diabetes. This finding suggests that a high carbohydrate/cassava intake (84% of a mean daily supply of 1916 calories) combined with a low protein consumption (8% of caloric supply) does not cause diabetes. This does not support the World Health Organisation hypothesis that malnutrition-related diabetes exists, at least not in this West African rural population.