(Université de Genève) Diabetes is characterised by a deficiency of insulin. The opposite is the case in congenital hyperinsulinism: patients produce the hormone in excessive quantities. This leads to chronic hypoglycaemia. The disorder can lead to serious brain damage and even death in the worst cases. A team at the University of Geneva (UNIGE), Switzerland, supported by the Swiss National Science Foundation has succeeded in describing the effects of a frequent genetic mutation in cases of congenital hyperinsulinism.