Gluconeogenesis is not regulated by either glucose or insulin in extremely low birth weight infants receiving total parenteral nutrition

Objective: To determine potential factors regulating gluconeogenesis (GNG) in extremely low birth weight infants receiving total parenteral nutrition.

Study design: Seven infants (birth weight, 0.824 ± 0.068 kg; gestational age, 25.4 ± 0.5 weeks; postnatal age, 3.3 ± 0.2 days) were studied for 11 hours, with parenteral lipid and amino acid therapy continued at prestudy rates. Glucose was supplied at prestudy rates for the first 5 hours (period 1) and was then reduced to 6 mg/kg·min for 1 hour and further to ~3 mg/kg·min for 5 hours (period 2). A total of 2.5 mg/kg·min of the glucose was replaced by [U-(13)C]glucose throughout the study for measurements of glucose production and GNG. Concentrations of glucose, insulin, glucagons, and cortisol were determined.

Results: GNG and glucose production remained unchanged (2.12 ± 0.23 vs. 1.84 ± 0.25 mg/kg·min [P = NS] and 2.44 ± 0.27 vs. 2.51 ± 0.31 mg/kg·min [P = NS], respectively), despite a 60% reduction of the glucose infusion rate and subsequent 30% (124.7 ± 10.8 to 82.6 ± 8.9 mg/dL; P = .009) and 70% (26.9 ± 4.7 to 6.6 ± 0.4 μU/mL; P = .002) decreases in glucose and insulin concentrations, respectively. Cortisol and glucagon concentrations remained unchanged.

Conclusion: In extremely low birth weight infants receiving total parenteral nutrition, GNG is a continuous process that is not affected by infusion rates of glucose or concentrations of glucose or insulin.