The plasma sugar, free fatty acid, cortisol, and growth hormone response to insulin and the comparison of this procedure with other tests of pituitary and adrenal function. II. In patients with hypothalamic or pituitary dysfunction or anorexia nervosa

The sequence of events that follows the intra-venous injection of insulin has been reviewed ex-tensively by De Bodo and Altszuler (1). A com-plex set of mechanisms normally operates to an-tagonize the action of insulin, thereby limiting the extent to which the blood glucose falls and causing a rapid return to original levels. There is evi-dence that glucocorticoids and growth hormone play an important role as hormonal insulin an-tagonists. Thus both Addison's disease and hypo-pituitarism are known to be associated with in-creased insulin sensitivity, whereas patients with Cushing's syndrome or acromegaly are resistant to its hypoglycemic action (2, 3). The observa-tion that the intravenous injection of insulin into control subjects results in rapid elevations of plasma cortisol (4, 5) and growth hormone (6-9) also supports the possible physiologic importance of these hormones as insulin antagonists. Since the release of these two hormones depends on ade-quate hypothalamic as well as pituitary and adrenal function (5, 7, 10), it was apparent that a rapid test of both the hypothalamo-pituitary-adrenal axis for the secretion of cortisol and the hy-pothalamo-pituitary axis for the secretion of growth hormone could be developed with insulin-induced hypoglycemia as a stimulus. The present paper describes the time sequence of the changes in plasma sugar, free fatty acids (FFA), cortisol, and growth hormone in normal * Submitted for publication September 21, 1965; ac