RESUMEN
The response of plasma insulin concentration to an oral glucose tolerance test (OGTT) and to the maximum stimulatory effect obtained with administration of glucose, glucagon and tolbutamide was studied in 24 siblings of diabetic children and in ten obese children. Five siblings of patients with diabetes sound to have chemical diabetes had hyperinsulinism during the OGTT. Serum insulin concentrations during the maximum stimulation of the beta cells in the children with chemical diabetes, although diminished at 15 minutes, were considered not significantly different from controls. Obese children had hyperinsulinism during the OGTT and the maximum stimulation of the beta cell. The data suggest that hyperinsulinism may precede or accompany carbohydrate intolerance in siblings of diabetic children.