EFFECTS OF LACTATE ON GLUCOSE-METABOLISM IN HEALTHY-SUBJECTS AND IN SEVERELY INJURED HYPERGLYCEMIC PATIENTS

Hepatic glucose production is autoregulated during infusion of glucone ogenic precursors. In hyperglycemic patients with multiple trauma, hep atic glucose production and gluconeogenesis are increased, suggesting that autoregulation of hepatic glucose production may be defective. To better understand the mechanisms of autoregulation and its possible a lterations in metabolic stress, lactate was coinfused with glucose in healthy volunteers and in hyperglycemic patients with multiple trauma or critical illness. In healthy volunteers, infusion of glucose alone nearly abolished endogenous glucose production. Lactate increased gluc oneogenesis (as indicated by a decrease in net carbohydrate oxidation with no change in total [C-13]carbohydrate oxidation) but did not incr ease endogenous glucose production. In patients with metabolic stress, endogenous glucose production was not suppressed by exogenous glucose , but lactate did not further increase hepatic glucose production. It is concluded that 1) in healthy humans, autoregulation of hepatic gluc ose production during infusion of lactate is still present when glycog enolysis is suppressed by exogenous glucose and 2) autoregulation of h epatic glucose production is not abolished in hyperglycemic patients w ith metabolic stress.