Effect of thymosin (fraction 5) on the plasma levels of glucose and glucoregulatory hormones in humans.

Several interactions between thymosin (fraction 5) and the endocrine system have been described in animals, but its effects in humans have not been studied. Plasma levels of glucose, insulin and glucagon were obtained in response to a glucose load before and after treatment with thymosin in eight patients. The glucose tolerance was normal in all subjects and remained so following thymosin administration. No significant changes in the levels of glucagon and insulin were obtained. In six patients, baseline levels of plasma cortisol and ACTH were also obtained. Four out of six patients demonstrated an increase in ACTH levels although the mean differences did not achieve statistical significance. Plasma cortisol levels also did not change significantly. We conclude that thymosin given over a short term is unlikely to significantly influence carbohydrate metabolism. Since four out of six patients showed an increase in basal ACTH levels, it suggests that thymosin may affect the hypothalamic pituitary/adrenal axis. However, further study is needed for complete evaluation of these effects.