The insulin:glucagon ratio and the secretion of growth hormone after intravenous administration of amino acids and carbohydrates in healthy subjects.

Abstract

In ten normal male subjects, the influence of amino acid and carbohydrate infusions on the plasma concentrations of glucose, free fatty acids, inorganic phosphate, insulin, glucagon, and growth hormone was studied. The molar insulin:glucagon ratio was calculated. Three different solutions were used: A mixture of 13 amino acids (50 g/l) = group I, solution (1) plus sorbitol (50 g/l) plus xylitol (50 g/l) = group II, and solution (1) plus glucose (100 g/l) = group III. According to Unger, the relative concentrations of insulin and glucagon control the hepatic glucose balance and the organism’s energy requirement. The insulin:glucagon ratio is inversely correlated with increased glucose production of the liver. A high ratio indicates glucose storage and increased protein synthesis, whereas a low one is a sign of increased gluconeogenesis from amino acids. Our data are in agreement with the clinical observation that, in parenteral nutrition, amino acids should be given together with carbohydrates to produce an anabolic effect. The insulin:glucagon ratio remained unchanged in group I and showed a rise from 6.4 to 14.8 in group II. In group III, a marked increase in the ratio was observed with a maximum of 46 after 60 minutes. Thus, in normal subjects, the combination of amino acids and glucose has a stronger effect on glucose storage and protein synthesis than the combination of amino acids and sorbitol and xylitol. The determination of the insulin:glucagon ratio can be useful for evaluating the anabolic effect of carbohydrate and amino acid solutions in parenteral nutrition.