EFFECTS OF PROPRANOLOL ON BLOOD SUGAR, INSULIN AND FREE FATTY ACIDS

Three types of experiment were carried out in normal subjects to determine the effect of therapeutic doses of oral Propranolol on 1. the blood sugar, plasma insulin and free fatty acids (FFA) during prolonged fasting and exercise, 2. intravenous glucose tolerance and the rise in insulin level after intravenous glucose, and 3. the intravenous glucose tolerance on exercise. Propranolol caused only slight lowering of the blood sugar in normals, even after 24 h fasting. This was most noticeable during exercise. There was no significant effect of Propranolol on fasting insulin levels, on glucose tolerance at rest or exercise, or on the response of plasma insulin levels to intravenous glucose. Lowering of plasma FFA levels was found in all subjects when taking Propranolol particularly during and after exercise. Possible mechanisms of hypoglycaemia in those cases reported in the literature are discussed. It is concluded that hypoglycaemia is not a major problem in Propranolol therapy. © 1969 Springer-Verlag.