Insulin-induced hypoglycemia in depression

Abstract

Insulin-induced hypoglycemia is a provocative test designed to assess neuroendocrine correlates of the “stress response.“ To study the biological manifestations of the “stress response“ in ten patients with depression and five patients with rapid cycling (RC) manic depression, serial sampling of blood was carried out following the intravenous administration of 0.15 p/Kg of regular insulin. Cortisol, ACTH, prolactin, and growth hormone responses to insulin-induced hypoglycemia were compared to 13 normal volunteers. Sampling for stress hormones was carried out at intervals of ten minutes for a period of 3.5 hours. Although basal pre-insulin glucose levels and absolute maximum decreases in glucose levels were not significantly different, neuropeptide responses were abnormal. Despite normal cortisol responses to insulin-induced hypoglycemia, ACTH responses were noted to be significantly attenuated in the depressed cohort. When compared to controls, prolactin and growth hormone responses were also noted to be attenuated in the depressed cohort. When ACTH responses in the RC cohort were compared to controls, peak responses were noted to be significantly augmented. When RC responses were compared to depressives, ACTH responses were also noted to be augmented. Prolactin and growth hormone responses were significantly attenuated compared to controls, but not different from depressives.