Glucose Counterregulatory Hormone Response During Hypoglycemia due to Endogenous Hyperinsulinemia

Background: In patients with hypoglycemia due to endogenous hyperinsulinemia such as insulinoma or insulin autoimmune syndrome, little is known about the counterregulatory hormone response to spontaneous hypoglycemia. We therefore compared hormone responses during spontaneous hypoglycemia due to endogenous hyperinsulinemia with those at the end of a 72-hour fast. Methods: We measured glucagon, epinephrine, cortisol, and growth hormone responses during spontaneous hypoglycemia in 8 patients with insulinoma and 18 patients with insulin autoimmune syndrome. We also assessed these responses in 13 normal control subjects who underwent a 72-hour fast. Results: In patients with insulinoma (median serum glucose level, 35.0 mg/dL), plasma glucagon levels (median, 42.9 vs. 76.2 pg/mL, respectively; P < 0.05) were lower than those in control subjects (serum glucose level, 62.5 mg/dL), whereas, there were no statistically significant differences in the other hormone responses between the two groups. In contrast, in the patients with insulin autoimmune syndrome (median serum glucose level, 34.5 mg/dL), plasma glucagon levels (median, 73.7 vs. 76.2 pg/mL, respectively) were lower than those in the control subjects, but there was no statistically significant difference between the two groups. There were no statistically significant differences in counterregulatory hormone responses during spontaneous hypoglycemia between patients with insulinoma and patients with insulin autoimmune syndrome. Conclusion: Our results suggest that defective glucagon secretion in patients with insulinoma rather than insulin autoimmune syndrome may contribute to hypoglycemia in addition to hyperinsulinemia. (J Korean