Abstract 185

Background: Because glucose production (GPR) in children is greater than in adolescents, we hypothesized that the rate of gluconeogenesis(GNG) and the fraction of GPR derived from GNG would also be increased in children.

Aim: 1. Measure GPR and GNG in children and adolescents, and 2. Determine the reproducibility of these measures when activity and diet were carefully controlled.

Subjects: 4 normal, prepubertal children (8±0.3 yrs, mean±SE), and 4 normal adolescents (15±0.5 yrs), 2 boys & girls in each group, were studied on 2 occasions after a 12 hrs fast preceded by 1 wk of constant dietary composition. The studies were separated by 3 - 4 wks.

Methods: GPR was measured with [1-13C]glucose tracer and GNG was estimated using 2H labeling of C6 of glucose after ingestion of deuterated water.

Results: In children and adolescents, respectively, GPR was 3.4±0.1(mean±SE) and 2.3±0.1 mg/kg min (Study 1), and 3.3±0.2 and 2.4±0.2 mg/kg min (Study 2); GNG was 1.8±0.1 and 1.2±0.1mg/kg min (Study 1), and 1.8±0.1 and 1.1±0.1 mg/kg min (Study 2). Adolescent GPR and GNG were less than the childhood values on both studies (p<0.01), but GNG was 52±1 and 51±6% of GPR (Study 1) and 53±3 and 47±5% of GPR (Study 2), (p=ns).

Conclusion: 1. GPR and GNG were higher in the prepubertal children but the fractions of GPR derived from GNG were nearly identical. 2. Under controlled conditions, postabsorptive GPR and GNG in children and adolescents are highly reproducible.