Quantification of gluconeogenesis in cirrhosis: response to glucagon.

BACKGROUND AIMS: Accelerated starvation and early recruitment of alternate fuels in cirrhosis have been attributed to reduced availability of hepatic glycogen. The aim of this study was to measure gluconeogenesis (as a marker of protein oxidation) in relation to total glucose production and glucagon-stimulated glycogenolysis. METHODS: Glucose and urea production, gluconeogenesis, and glycogenolysis were calculated using stable isotope methods before and during glucagon infusion (3 ng. kg-1. min-1) in 5 cirrhotic patients and 5 matched controls before and after glycogen repletion. RESULTS: In the basal state, cirrhotic patients had a normal rate of glucose production, but the contribution of gluconeogenesis was increased (74.3% +/- 4.1% vs. 55. 6% +/- 12.1%; P < 0.005). Glycogen repletion normalized the rate of gluconeogenesis. The glycemic response to glucagon (3 ng. kg-1. min-1) was blunted in cirrhotic patients because of a lower rate of glycogenolysis (0.63 +/- 0.23 vs. 1.22 +/- 0.23 mg. kg-1. min-1; P < 0.01) and was not affected by glycogen repletion. Despite increased gluconeogenesis, the simultaneously measured rate of urea synthesis was lower in cirrhotic patients (3.11 +/- 1.02 vs. 5.0 +/- 1.0 mg/kg; P < 0.05). CONCLUSIONS: These data show that in cirrhosis, glucose production is sustained by an increased rate of gluconeogenesis. The hepatic resistance to glucagon action is not caused by reduced glycogen stores.