Morphine-induced hyperglycemia: role of insulin and glucagon.

An iv bolus injection of 0.5 mg/kg morphine, about twice the therapeutic dose, caused plasma glucose to rise more than 120 mg/dl in alloxan-diabetic conscious dogs but had little effect on conscious normal dogs. Plasma glucagon rose in the diabetic and nondiabetic groups by 30 +/- 10 and 100 +/- 29 pg/ml, respectively, but insulin levels increased significantly only in the nondiabetics. The hyperglycemic action on morphine may, at least in part, be the result of an increase in glucagon secretion without a sufficient accompanying release of insulin.