ABSTRACTThe glycemic and insulin response to an oral glucose load was studied in 17 children with acute lymphoblastic leukemia (ALL) and 13 normal controls. The patients were randomly assigned to either group A, receiving prednisone and vincristine, or group B, receiving these agents and, in addition, L-asparaginase from days 9–19 of the study. The glucose load was performed prior to (phase I), and on days 8 (phase II), and 19 (phase HI) of chemotherapy. The mean glycemic response in both groups of patients was significantly higher than in controls at diagnosis and prior to any treatment, while mean insulin levels were not significantly different from controls. One week after initiation of treatment, the mean glycemic response improved, and was associated with hyperinsulinism. After the second week of treatment, the mean glucose and insulin response curves in group A were similar to controls. In group B, while insulin values returned to normal, blood glucose levels remained higher than in controls, but not significantly so. These findings suggest that: 1) The leukemic process itself, through mechanisms as yet undetermined, causes impairment of glucose tolerance, and 2) the diabetogenic effect of L-asparaginase is not manifested in all patients.