Insulin resistance and body composition in preterm born children during prepubertal ages

Background Premature born children may show insulin resistance in childhood which may be due to intrauterine or postnatal adverse environmental factors. Objective Aim of this study was to evaluate insulin resistance and body composition in preterm born children born appropriate for gestational age (AGA) or small for gestational age (SGA) and relations with IGF-I, IGFBP-3 axis. Methods Ninety-three preterm born children grouped as premature SGA (n = 30) and premature AGA (n = 63) were evaluated at age 4.6 +/- 0.2 years and 4.7 +/- 0.1 years with respect to their glucose, insulin, IGF-I, IGFBP-3, IGFBP-1, leptin levels and body composition by dual-energy X-ray absorptiometry. Their data were compared to that of body mass index (BMI) matched term SGA (n = 42) and term AGA (n = 44) children of age 4.5 +/- 0.2 and 3.8 +/- 0.1 years. All children had height appropriate for their target height. Insulin resistance was evaluated by basal insulin and homeostasis model assessment for insulin resistance (HOMA-IR). Results Basal insulin level was similar in preterm AGA (4.3 +/- 1.4 pmol/l) and term AGA (7.9 +/- 6.4 pmol/l) children at similar and normal BMI levels. Preterm SGA children had insulin levels (5.0 +/- 3.6 pmol/l) similar to preterm AGA children but significantly lower than that in term SGA children (23.7 +/- 20.8 pmol/l) (P = 0.001). Similar results were obtained for HOMA-IR. Term SGA children had also significantly lower IGFBP-1 levels. Body composition, leptin and IGFBP-3 did not differ between the respective groups. IGF-I was lower in preterm AGA (5.0 +/- 0.6 nmol/l) than in term AGA (8.3 +/- 1.2 nmol/l) (P < 0.001) children. Conclusions Premature born AGA and SGA children do not have insulin resistance when compared to term children if they have made a catch-up growth appropriate for their target height and have normal BMI. The similar insulin levels in preterm SGA and preterm AGA children together with increased insulin levels in term SGA children points to the fact that it is the intrauterine restriction in the third trimester that has an adverse effect on future adverse metabolic outcome.