Serum somatomedin and insulin levels in tumor hypoglycemia.

Serum concentrations of somatomedin and immunoreactive insulin were measured during the hypoglycemic phase of 3 patients with tumor hypoglycemia. Normal amounts of somatomedin were detected in their fasting sera, but they may have been inappropriate (or associated with enhanced insulin-like activity) considering the degree of hypoglycemia. Fasting serum insulin levels were consistently depressed, and in two of the cases remained low even after an oral glucose load. Nevertheless, the blood glucose concentrations of these two patients fell to hypoglycemic levels again by 3 hours; the mechanism of this reactive hypoglycemia remains unclear.