HYPERINSULINISM has been said to be the most common cause of persistent hypoglycaemia in infants during the first year of life’. It is a diagnosis of importance, since a number of authors have emphasised the high incidence of permanent neurological damage in~ urvivorsl-~. The purpose of this annotation is to review recent advances in understanding the pathophysiology of this condition and to present some guidelines for investigation and manage men t.

Hyperinsulinism occurs commonly in newborn infants of mothers with poorly controlled diabetes, and also in infants with erythroblastosis fetalis and the Wiedemann-Beckwith syndrome. However, the hyperinsulinism of these infants is usually transient and normal blood-glucose homeostasis is established eventually. Persistent hyperinsulinism is more uncommon and is due to a structural abnormality of the endocrine pancreas. The hypoglycaemia caused by this form of hyperinsulinism is exceedingly difficult to control, and most infants eventually have been submitted to laparotomy and partial or total pancreatectomy.