The effect of E. coli L-asparaginase on oral glucose tolerance and insulin release in man

To study the effect of E. Coli L-asparaginase on glucose tolerance and insulin release, 6 patients with neoplastic disease were subjected to 3 hour oral glucose tolerance tests with simultaneous measurement of serum immunoreactive insulin (IRI) levels before and following the intravenous administration of 5000 I. U. L-asparaginase/day for 4 days. Five of the patients exhibited a significant deterioration in glucose tolerance; however, no change was noted in their fasting glucose and IRI levels. The deterioration in glucose tolerance was associated with a decrease in the amount of insulin secreted in the first 30 minutes after the oral glucose load. The total amount of insulin released during the 3 hour test remained unchanged. These studies suggest that L-asparaginase can cause a deterioration of glucose tolerance without accompanying fasting hyperglycaemia. This may be due, in part, to a decrease in glucose-induced insulin release during the first thirty minutes following oral glucose.