SPONTANEOUS hypoglycemia in infancy may, on rare occasions, be precipitated by the ingestion of casein, L-leucine or isovaleric acid, an intermediary metabolite of leucine.1 2 3 4 Recently, this phenomenon of "leucine-induced hypoglycemia" was observed to be associated with a rise in plasma insulin level.5 , 6 A case of leucine-induced hypoglycemia in an infant who, at autopsy, showed hyperplasia of pancreatic islet cells is reported below. In addition the patient had massive bilateral subdural hematomas, with cerebral atrophy. Case Report P.C., a 3 1/2-month-old female Negro infant, was admitted to the Clinical Center of the National Institutes of Health on July 13, 1959, because . . .