Causes and evaluation of tumor-induced hypoglycemia.

We treated four patients who had hypoglycemia and nonpancreatic tumors. Two had pleural mesothelioma, one had primary fibrosarcoma of the liver, and one had pheochromocytoma metastatic to the liver. We propose four mechanisms for this syndrome: (1) insulin or insulin-like activity produced by the tumor, (2) decreased gluconeogenesis, (3) disruption of glucagon metabolism, and (4) increased utilization of glucose by the tumor. The local effects of the tumor in hepatic parenchyma may also play an important role. The important diagnostic tests are an insulin-glucose ratio, to rule out insulinoma, and fasting glucose levels. An assay of nonsuppressible insulin-like activity can be performed and is of investigative interest, but does not aid in individual patient therapy. Treatment consists of control of the tumor.