ABSTRACT
The course of illness of a male infant who lived for seven months with a diffuse, nesidioblastic hyperplasia of pancreatic islets is described. Before surgical intervention the diagnosis should be ascertained by 1. observation of acetonuria which is always absent after hypoglycemic episodes, 2, the typical constellation of insulin concentration, free fatty acid concentration and beta-hydroxybutyrat during a hypoglycemia (as found by Baker et al. 1976) and/or by simultaneous measuring of glucose-insulin levels under the conditions of fasting as well as of oral leucine, oral glucose and intravenous tolbutamide loading. Therapy with diazoxide should be tried in any case. If all conservative measure fail and relative or absolute hyperinsulinemia is proved, experience shows that an immediate operation is indicated.