Hypoglycemia associated with extrapancreatic tumors. Report of two cases with studies on its pathogenesis.

Abstract

Two patients having hypoglycemia associated with extrapancreatic tumors have been described. Patient 1 had poor serum insulin response following the intravenous administration of glucose and tolbutamide and poor growth hormone response to hypoglycemia. The isotopic studies revealed markedly augmented glucose and lactate turnover rates but diminished glucose recycling, indicating inhibited gluconeogenesis. The hypoglycemia was attributed to increased glucose requirements, inhibition of gluconeogenesis, and failure of hormonal homeostasis. The tumor extract revealed nonsuppressible insulin-like activity but no immunoassayable insulin, and failed to produce hypoglycemia in mice in vivo. Patient 2 had adequate serum insulin response following the intravenous administration of glucose. The isotopic studies revealed markedly augmented glucose and lactate turnover rates, as well as increased recycling. The hypoglycemia was attributed to increased glucose requirements. There was no evidence of the inhibition of gluconeogenesis. These studies indicate that hypoglycemia produced by extrapancreatic tumors is multifactorial in etiology and its mechanism varies in different patients.