The insulin-antagonistic effect of the counterregulatory hormones.

The counterregulatory hormones glucagon, adrenaline, cortisol and growth hormone are released during hypoglycaemia, and under other stress conditions. These hormones have insulin-antagonistic effects both in the liver and in the peripheral tissues. The insulin-antagonistic effects of glucagon and adrenaline are of rapid onset, whereas those of cortisol and growth hormone are only observed after a lag period of several hours. Glucagon is the most important hormone for acute glucose counterregulation. When the release of this hormone is deficient, as in patients with insulin-dependent diabetes, adrenaline becomes the most important hormone for glucose recovery during hypoglycaemia. Cortisol and growth hormone contribute to counterregulation during prolonged hypoglycaemia, but adrenaline is also of utmost importance in this condition. Adrenaline induces the early posthypoglycaemic insulin resistance, whereas cortisol and growth hormone are important for the insulin resistance that is observed later following hypoglycaemia. However, the importance of posthypoglycaemic insulin resistance for induction of posthypoglycaemic hyperglycaemia in clinical situations is limited. The pronounced insulin-antagonistic effect of growth hormone indicates that this hormone, in addition to its effect on the dawn phenomenon, could also play a key role in the regulation of other diurnal rhythms of glucose metabolism.