Gluconeogenesis is Not Regulated by Either Glucose or Insulin in Extremely Low Birth Weight Infants Receiving Total Parenteral Nutrition

ObjectiveTo determine potential factors regulating gluconeogenesis (GNG) in extremely low birth weight infants receiving total parenteral nutrition.Study designSeven 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-13C]glucose throughout the study for measurements of glucose production and GNG. Concentrations of glucose, insulin, glucagons, and cortisol were determined.ResultsGNG 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.ConclusionIn 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.