EFFECTS OF INFUSED AMINO-ACIDS AND LIPIDS ON GLUCOSE-METABOLISM IN HEALTHY LEAN HUMANS

The effects of infusion of a triglyceride emulsion (which induces peri pheral insulin resistance) and amino acids (which stimulate gluconeoge nesis) on glucose metabolism were investigated in healthy lean humans during exogenous infusion of glucose. One group of subjects (n = 5) wa s infused for 7.5 h with 11.1 mu mol/kg/min glucose; during the last 4 h, amino acids were also infused at a rate of 3.33 mg/kg/min. A secon d group of subjects (n = 5) was infused with glucose + lipids (Lipoven os(R), 10% 10 ml/min) for 7.5 h and amino acids were added during the last 4 h. Infusion of lipids suppressed the increase in glucose oxidat ion observed during infusion of glucose alone (Delta glucose oxidation : -2.1 +/- 1.1 vs. + 4.5 +/- 1.4 mu mol/kg/min; P < 0.05) and during i nfusion of glucose + amino acids (Delta glucose oxidation: + 1.6 +/- 1 .4 vs. + 10.6 +/- 1.2 mu mol/kg/min; P < 0.05). Gluconeogenesis (deter mined from C-13 glucose synthesis during infusion of C-13 bicarbonate) increased from 1.1 +/- 0.2 mu mol/kg/min during infusion of glucose a nd 1.6 +/- 0.3 during infusion of glucose + lipids to 3.2 +/- 0.4 and 3.1 + 0.4, respectively, when amino acid infusion was superimposed (P < 0.05 in both instances). Plasma glucose concentrations were identica l during infusion of glucose alone or glucose + amino acids, with or w ithout lipids. Insulin concentrations were significantly increased by lipids both during infusion of glucose alone and of glucose + amino ac ids. It is concluded that infusion of lipids + amino acids in healthy subjects results in both a peripheral insulin resistance and an increa sed gluconeogenesis; however, these alterations, similar to those enco untered in non-insulin dependent compensated diabetes mellitus, are co mpensated for by an increased insulin secretion, resulting in normogly cemia.