We are supporting World Diabetes Day. Diabetes affects the lives of many individuals diagnosed with congenital hyperinsulinism. Up to 53% of individuals develop hyperglycaemia following near-total pancreatectomy and for some, this will progress to insulin-treated diabetes. Individuals with dominantly inherited K-ATP channel mutations and hyperinsulinism due to a HNF4A mutation are also at increased risk of developing diabetes in early adulthood.