Until recently, there was a paucity of data on the epidemiology of diabetes mellitus in Africa. Over the past decade, information on the prevalence of type 2 diabetes has increased, albeit still limited, but there is still a lack of adequate data on type 1 diabetes in sub-Saharan Africa (SSA). For type 2 diabetes, although the prevalence is low in some rural populations, moderate and even high rates have been reported from other countries. In low diabetes prevalence populations, the moderate to high rates of impaired glucose tolerance is a possible indicator of the early stage of a diabetes epidemic. Diabetes prevalence is higher in urban, migrant and African-origin populations living abroad. There is evidence for a significant association with preventable and modifiable risk factors viz. adiposity, known diabetes, physical activity; but a dearth of data on the impact of dietary and genetic factors. For type 1 diabetes, the limited available data suggest that in SSA the frequency is low and that age of onset occurs later than in the western world. There is evidence for the role of genetic and immunological factors in its pathogenesis. The impact of HIV/AIDS on projected estimates for diabetes prevalence in Africa needs to be established.