Effect of epinephrine on glucose metabolism in humans: contribution of the liver

Abstract

Epinephrine causes a prompt increase in blood glucose concentration in the postabsorptive state. This effect is mediated by a transient increase in hepatic glucose production and an inhibition of glucose disposal by insulin-dependent tissues. Epinephrine augments hepatic glucose production by stimulating glycogenolysis and gluconeogenesis. Although its effect on glycogenolysis rapidly wanes, hyperglycemia continues because the effects of epinephrine on gluconeogenesis and glucose disposal persist. Epinephrine-induced hyperglycemia is markedly accentuated by concomitant elevations of glucagon and cortisol or in patients with diabetes. In both cases, the effect of epinephrine on hepatic glucose production is converted from a transient to a sustained response, thereby accounting for the exaggerated hyperglycemia. During glucose feeding, mild elevations of epinephrine that have little effect on fasting glucose levels cause marked glucose intolerance. This exquisite sensitivity to the diabetogenic effects of epinephrine is accounted for by its capacity to interfere with each of the components of the glucoregulatory response, i.e., stimulation of splanchnic and peripheral glucose uptake and suppression of hepatic glucose production. Our findings suggest that epinephrine is an important contributor to stress-induced hyperglycemia and the susceptibility of diabetics to the adverse metabolic effects of stress.