Longitudinal association between IGFBP-1 levels and parameters of the metabolic syndrome in obese children before and after weight loss

Background. Insulin-like growth factor binding protein 1 (IGFBP-1) is a marker of insulin resistance. We hypothesized that IGFBP-1 is associated with the metabolic syndrome (MetS), which is related to insulin resistance. Methods. We examined 51 obese Caucasian children (mean age 12.1 +/- 2.3, 55% male, mean body mass index [BMI] 31.8 +/- 4.8 kg/m(2)). Anthropometrical markers, pubertal stage, hepatic ultrasound, waist circumference, blood pressure, fasting serum IGFBP-1, IGFBP-3, IGF-I, adiponectin, leptin, transaminases, glucose, insulin, triglycerides, and HDL-cholesterol concentrations were determined at onset and the end of the one-year lifestyle intervention. Results. In contrast to IGF-I and IGFBP-3, IGFBP-1 correlated significantly to most parameters of the MetS in cross-sectional (waist circumference: r = -0.45, triglycerides: r = -0.29; insulin: r = -0.31; HOMA: r = -0.30) and longitudinal analyses (Delta triglycerides: r = -0.22;Delta Insulin: r = -0.25;. HOMA: r = -0.62). The association between changes of HOMA and changes of IGFBP-1 was stronger than the associations between changes of leptin or adiponectin, and changes of HOMA. The risk for the MetS was inversely related to IGFBP-1 levels (odds ratio: -0.05 per additional IGFBP-1 unit; 95% confidence interval: -0.08 up to -0.02; p = -0.019) in a multiple logistic regression analyses adjusted to BMI, pubertal stage, age, and gender. The nine obese children with the MetS had significantly lower IGFBP-1 levels (1.6 +/- 1.3 ngm/l) than the 42 obese children without the MetS (4.0 +/- 3.8 ng/ml). The eleven obese children with fatty liver assessed by ultrasound had significantly lower IGFBP-1 levels (1.5 +/- 1.3 ngm/l) than the 40 obese children without fatty liver (4.2 +/- 4.1 ng/ml). Conclusion. The strong relationships between IGFBP-1, insulin resistance, and the MetS suggest that IGFBP-1 might be a promising marker for these entities in obesity. This study is registered at clinicaltrials.gov (NCT00435734).