Summary and Introduction
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.
Term babies who are small for gestational age (SGA) have been shown to develop insulin resistance and other morbidities including type 2 diabetes mellitus, hyperlipidaemia, hypertension and coronary heart disease in adult life.[1,2] In addition to adverse intrauterine environment, the role of postnatal catch-up growth (CUG) has also been implied in the developing morbidities.[3,4,5] Rapid growth especially in the first 2 years of life contributes to insulin resistance especially if accompanied by increased body mass index (BMI).[6,7] Even if BMI is normal, body fat mass and fat distribution are important determinants of insulin sensitivity.[8,9] Insulin resistance, the hallmark of these abnormalities, is an early pathology starting in early childhood in SGA born children.[10,11] Recent studies have shown that early life events may have an effect on the maturation of GH/IGF-I axis and abnormalities in somatotropic axis may contribute directly to reduced insulin sensitivity. Abnormalities in leptin secretion in relation to BMI have also been reported in term SGA born children and adults, and was attributed to the effects of early perinatal events on adipocytes.[13,14] These studies have been mainly done in term SGA infants.
In contrast to SGA babies who experience an adverse intrauterine environment, preterm babies who face an adverse postnatal environment have also been shown to be equally adversely affected exhibiting a decrease in insulin sensitivity in early childhood.[15,16,17] However, it is not still clear whether in premature born children it is the adverse intrauterine period or the early postnatal period that is responsible for the future consequences. In this study, we aimed to evaluate insulin resistance, IGF axis and body composition in preterm born children who have not experienced adverse intrauterine environment, that is, born appropriate for gestational age (AGA), and also in those who have experienced intrauterine growth restriction and born SGA and compare their data with that of term children.
Clin Endocrinol. 2008;68(5):773-779. © 2008 Blackwell Publishing
Cite this: Insulin Resistance and Body Composition in Preterm Born Children During Prepubertal Ages - Medscape - May 01, 2008.