Epidemiology of type 1 diabetes and its complications. The prevalence of type 1 diabetes in adult is estimated at 0.3 to 0.5%, or 10% of all types of diabetes. In youth less than 15 years, in France, the incidence of type 1 diabetes is 18 per 100,000 over the period 2013-2015 (based on the National Health Data System), corresponding to an approximate prevalence of 1.3 per 1000. The incidence of diabetes in youth increases by 3 to 4% per year, an increase seen in France since 1988. With the intensification of treatment (resulting in HbA1c around 8% on average over the entire follow-up), after 30 years of progression of diabetes (in subjects aged 50 years on average), it was observed that the prevalence of severe retinopathy (requiring laser treatment) was nearly 15%, microalbuminuria 15%, macroproteinuria 4%, advanced renal failure less than 2%, clinical neuropathy 24%, and macrovascular complications around 5%.