SERUM CONCENTRATIONS OF INSULIN, INSULIN-LIKE-GROWTH-FACTOR (IGF)-I, IGF BINDING-PROTEIN (IGFBP)-1 AND -3 AND GROWTH-HORMONE BINDING-PROTEIN IN OBESE CHILDREN - FASTING IGFBP-1 IS SUPPRESSED IN NORMOINSULINEMIC OBESE CHILDREN

OBJECTIVE Simple obesity is characterized by normal or accelerated gro wth in the presence of reduced serum levels of GH, whereas its detaile d mechanism remains unknown. We, therefore, evaluated interrelationshi ps among serum levers of insulin, IFG-I, IGF binding protein (IGFBP)-1 and -3 and growth hormone binding protein (GHBP) in prepubertal obese children. SUBJECTS Prepubertal 20 obese children and 20 age-matched c ontrol children were included in the study, RESULTS Serum levels of in sulin, IGF-I and IGFBP-3 in obese children did not differ from those i n controls. The serum revel of IGFBP-1 was significantly lower in obes e children (22.1 +/- 18.4 mu g/l, P<0.001) than in control children (7 6.0 +/- 62.9 mu g/l). No relationship was found between the serum leve ls of insulin and IGF-I, IGFBP-1, or IGFBP-3 in obese subjects, The se rum revel of GHBP in obese children was significantly elevated as comp ared with that in controls and was positively correlated with body mas s index (BMI). No relationship was found between the serum levels of G HBP and IGF-I in obese subjects. CONCLUSIONS The present study showed for the first time that the fasting IGFBP-1 level was suppressed in pr epubertal obese children with fasting normoinsulinaemia, We speculate that the hyperinsulinaemia which cannot be detected in the fasting sta te may have suppressed hepatic production of IGFBP-1, Alternatively, t he reduced IGFBP-1 is likely to be a compensatory response to impaired insulin sensitivity, Thus, the IGFBP-1 level may be a useful predicto r for the early identification in the development of insulin resistanc e in prepubertal obese children.