GROWTH FACTORS AND ADIPOCYTOKINES IN PRE-PUBERTAL CHILDREN BORN SMALL-FOR-GESTATIONAL AGE: RELATION TO INSULIN RESISTANCE

Abstract

Objective: The aim of this study was to test whether being born small-for-gestational age (SGA) has an impact on adiponectin and leptin levels and the insulin-like growth factor (IGF)–system in relation to insulin sensitivity, taking into consideration the severity of growth restriction.

Research Design and Methods: Serum levels of adiponectin, leptin, fasting glucose, insulin (I_F), the homeostasis model assessment insulin resistance index (HOMA-IR), IGF-1, free IGF-1, IGF binding protein-1 and −3 (IGFBP-1, −3), total cholesterol, HDL-cholesterol, LDL-cholesterol and triglycerides, were evaluated in 57 children at age 4-10 years. Of these 32 had been born appropriate-for-gestational age (AGA) and 25 SGA (<3^rd percentile 14, 3^rd-10^th percentile 11).

Results: The SGA 3^rd–10^th percentile children were already insulin resistant at prepubertal age (I_F 39.6±16.8vs 27±12pmol/L, p<0.01 and HOMA-IR 1.4±0.6vs 0.95±0.42 in AGA children, p<0.05). Their IGF-1 and IGFBP-3 concentrations were significantly lower than those in AGA children (160.4±66.2vs 207±66.8 μg/L, p<0.05 and 2.3±0.4vs 3.51±1.21 mg/L in AGA, p<0.01). The SGA<3^rd percentile had higher adiponectin (15.6±5.7 mg/L, p<0.05) and IGFBP-1 levels (113.5±33.9 μg/L, p<0.05) than AGA children (11.3±6.6 mg/L and 90.8±24.2 μg/L, respectively) and lower IGF-1 and IGFBP-3 concentrations (162.6±68.4 μg/L, p<0.05 and 2.4±0.7 mg/L, p<0.01). They also had significantly lower waist circumference (WC) (p<0.05). Leptin levels did not differ between groups, but an inverse correlation with IGFBP-1 (r=-0.55, p<0.01) was found in the pooled SGA group.

Conclusion: Intrauterine growth restriction appears to affect the IGF-axis at the pre-pubertal age and its severity plays a role in insulin sensitivity.