Background: Data on diabetes mellitus in general population in Benin is scarce. This study aimed therefore to assess prevalence and risk factors of diabetes mellitus in Benin. Methods: The study consisted of a cross-sectional survey, using the World Health Organisation (WHO)’s instrument for stepwise surveillance (STEPS) of non-communicable diseases risk factors. A five-stage random sample of 25 to 64 years old male and female adults living in Benin participated in structured interviews and their size, weight and blood pressure were measured according to standardized procedures. Glycaemia was measured using ACCUTREND? test strips for capillary blood glucose. Prevalence and means were computed with their 95% confidence interval and standard error respectively, taking into account the sampling design. Prevalence was compared by Khi2 and means by Student’s t test. Univariate and multivariate logistic regressions were performed to identify socio-demographic diabetes’s risk factors. Results: A total of 3772 adults participated in the study. The average age of respondents was 44.2 years. Overall, 68.3% of subjects were illiterate, 82.4% lived in rural areas, 82.57% were self-employed, 20% overweight, 7.51% obese and the prevalence of hypertension was 29.5 p.100. The prevalence of diabetes mellitus was 1.4 p.100 [CI95% = (0.94:2.05)]. This prevalence was higher in men than in women (2.1% vs. 0.8%, p = 0.0031). This prevalence was higher in urban areas than in rural areas. The Littoral department had the highest prevalence (3.4%), followed by the Collines department (2.7%), Donga (2.4%) and Borgou (2.3%). As many as 49.3% of subjects diagnosed with diabetes mellitus were not aware of their status. The age group of 56 - 64 years had the highest risk [OR = 6.6, IC95% = (1.6;22.4)]. The risk of diabetes was higher in people living in urban areas than in people living in rural areas [OR = 3.04 CI95% = (1.6;6.0)]. After controlling for confounding factors, risk factors of diabetes were gender, men being more at risk tha