Congenital hyperinsulinism (CHI) is the most frequent cause of a severe persistent hypoglycemia in newborn and children. In 25-40 % of patients the disease leads to severe and often irreversible effects such as delayed development, mental retardation or in some cases, death. CHI is caused through deregulated insulin secretion either from, discrete island shaped  regions of the pancreas, or from the entire pancreas. The first type described above is called the ?focal form?, the last one the ?diffuse form?. In most countries the estimated incidence is 1:50.000 to 1:25.000. In some ethnical groups, with high consanguinity, it is around 1:2.500.

There are two groups of CHI with different etiologies depending on the causative mutation. In the first group, mutations in the ABCC8- and KCNJ11-genes lead to a defective ATP-dependant potassium-ion channel in the beta cells (KATP-HI), in the other group, mutations in the GCK- or GLUD1-genes lead to an increased ATP/ADP-ratio in the beta cells, causing strong insulin secretion. Mutations in one of these four genes account for over 99 % of CHI cases. Most drug therapies for diabetes cannot be used to treat this condition as they often target this defective ion channel. Depending on the molecular pathogenesis, prognosis and treatment of the disease vary. Usually treatment consists of part resection, or even the complete resection, of the pancreas.