The effects of euglycemic hyperinsulinemia and amino acid infusion on regional and whole body glucose disposal in man

We investigated the effects of amino acid infusion on regional and whole body glucose metabolism in 16 normal volunteers, age 32 to 70 years. Ten subjects underwent 140-minute euglycemic insulin infusions at the rate of 1 mU/kg · min with concomitant 10% amino acid infusion. Six volunteers who underwent identical euglycemic insulin infusions without amino acid infusion served as controls. Whole body glucose disposal was estimated by the rate of exogenous glucose infusion required to maintain euglycemia, and peripheral glucose balance was evaluated by the forearm balance technique. In four subjects from each group, a primed, continuous infusion of [3-³H]glucose was used to quantify endogenous glucose production (EGP). Comparable states of hyperinsulinemia were achieved with insulin concentrations (μU/mL) of 101 ± 7 observed in the group with amino acid infusion and 95 ± 14 in the control group. Whole body glucose utilization was significantly lower (P < .001) in the subjects receiving amino acid infusion (5.0 ± 0.4 mg/kg · min) compared with the control group (8.7 ± 0.8 mg/kg · min). Forearm glucose disposal was markedly reduced (P < .05) in the group receiving amino acid infusion ( 1,385 ± 330 nmol 100 g · min) compared with controls ( 2,980 ± 460 nmol 100 g · min). Under comparable conditions of euglycemia and hyperinsulinemia, virtually complete suppression of EGP was observed in both groups. We conclude that infusion of amino acids with insulin under euglycemic conditions reduces whole body glucose utilization primarily by reducing peripheral glucose disposal.