In 1999, the prevalence of treated diabetes was 3.2% in the general population and 11.2% among people aged 65 and older living in mainland France. Population aging and the rise in obesity (a risk factor for type 2 diabetes) could lead to a significant increase in the prevalence of diabetes in the future. A sharp increase in the number of people with diabetes would cause major challenges in terms of medical care and costs. Providing prevalence estimates and projections for treated diabetes helps plan patient care and guide prevention efforts. The objective of this study is therefore to predict the prevalence of treated diabetes in mainland France through 2016, taking into account both demographic projections and the increase in obesity prevalence over time. (Introduction)