Relation of birth weight to fasting insulin, insulin resistance, and body size in adolescence.

Abstract

A relationship between birth weight and the insulin resistance syndrome has been reported in adults but has not been defined in adolescents. Data were analyzed in 296 children (132 girls and 164 boys) mean age 15.0 +/- 1.2 years who had euglycemic insulin clamp studies (intravenous administration of 1 mU. kg(-1). min(-1) of insulin balanced by a variable infusion of 20% glucose to maintain blood glucose at 100 mg/dl). Insulin sensitivity (M(LBM)) was determined by glucose uptake per kg lean body mass (LBM), and parents reported birth weight. Birth weight ranged from 1,021 to 4,848 g (mean +/- SD 3,433 +/- 551), with 4.0% <2,500 g. Fat mass and BMI had U-shaped relations with birth weight after adjustment for race, age, sex, and blood pressure. Lean mass index (lean mass/height squared) was stable across birth weight quartiles. Fasting insulin decreased nonsignificantly across birth weight quartiles but became significant after adjustment for adolescent weight (P = 0.008). Although M(LBM) was highest in the highest birth weight quartile, the pattern was not significant. Triglycerides tended to increase with birth weight, whereas LDL cholesterol (LDL-C) and HDL cholesterol (HDL-C) tended to decrease. Blood pressure was unrelated to birth weight. In this cohort, fat mass was greater in adolescents with low and high birth weight; fasting insulin was lower with higher birth weight after adjustment for adolescent weight. Insulin sensitivity increased nonsignificantly with birth weight.