The Influence of Blood Glucose on ACTH Secretion in Man

Abstract

In man Cortisol is necessary for a normal neoglycogenesis and fasted patients with adrenocortical insufficiency develop hypoglycemia. ACTH, among other hormones, is released during the course of severe insulin-induced hypoglycemia.

However, it is not proven that the ACTH secretion is implicated in the moment-to-moment maintenance of blood glucose.

The variations in plasma ACTH levels determined by radioimmunoassay have been studied:
a) in response to oral - or intravenous - glucose administration. It was found, that neither orally nor intravenously administered glucose suppresses plasma ACTH levels in normal subjects as well as in those with elevated ACTH values after administration of Metyrapone.
b) in 20 healthy subjects after administration of various doses of insulin. A significant rise in plasma ACTH levels is observed only if blood glucose falls below 45 mg/100 ml, and is not correlated with the magnitude of this fall nor the degree of hypoglycemia but with the clinical symptoms of stress.

ACTH secretion does not appear to be involved in the instant maintenance of blood glucose level as HGH does. Furthermore, in one patient with documented isolated HGH deficiency insulin-induced hypoglycemia is not corrected at 90 minutes in spite of a striking rise is plasma ACTH.

Key words

Corticotropin - Blood Glucose - Insulin Tolerance Test - Radioimmunoassay