Glucose production, gluconeogenesis, and insulin sensitivity in children and adolescents: An evaluation of their reproducibility

The prevalence of overweight and obese children has doubled, and the incide nce of type 2 diabetes in children (0-19 y) has increased 4-fold during the past several decades. As a result we can anticipate an increased number of metabolic studies in children. There are few data on measures of glucose m etabolism in normal children, and virtually none relating to their reproduc ibility. The aims of this study were 1) to provide new data on energy expen diture and glucose, lipid, and protein metabolism in nonobese, healthy chil dren and adolescents; 2) to evaluate their reproducibility; and 3) on the b asis of these data, to perform power calculations for metabolic studies. Ei ght nonobese subjects (8-16 y) were studied on two occasions, preceded by 7 d of a diet with identical energy content and macronutrient distribution. Gluconeogenesis, measured by deuterium oxide, accounted for 50% of glucose production. Insulin sensitivity, measured by the labeled minimal model, ave raged 4.9 x 10(-4) mL(mU.min)(-1). Glucose appearance rate was significantl y higher (p < 0.01) in the children than in the adolescents. Furthermore, w e demonstrated that for energy intake and expenditure, plasma concentration s of glucose and C-peptide, and rates of appearance of glucose and leucine, a 10% difference can be detected in fewer than five subjects with a power of 80% and a type I error of 5%. Insulin concentration, gluconeogenesis, in sulin secretory indices, insulin sensitivity, and glucose effectiveness wer e more variable, but with the above power a difference of 25% could be dete cted in 7-11 subjects using a paired study design.