The relationship between serum-free insulin- like growth factor-1 and metabolic syndrome in school adolescents of northeast China.

Purpose: Free insulin-like growth factor-1 (IGF-1) ratio (the ratio of IGF-1/insulin-like growth factor binding protein-3 [IGFBP-3]) was shown to be negatively correlated with metabolic syndrome (MetS) in adults, but it was unknown in Chinese adolescents. Patients and methods: The cross-sectional study enrolled 701 healthy school students (aged 12-16 years, 46.1% females) and 93 of them (18-22 years old, 46.2% females) were followed after 5 years. Results: In the cross-sectional study, the IGF-1/IGFBP-3 ratios were found correlated with low-density lipoprotein cholesterol (LDL-C; r=-0.071, P<0.05) and diastolic blood pressure (r=-0.077, P=0.034). A lower IGF-1/IGFBP-3 ratio was an independent risk factor for MetS (OR=2.348, 95% CI: 1.040-5.303), hypertension (OR=1.729, 95% CI: 1.040-5.303), and increased LDL-C (OR=1.841, 95% CI: 1.230-2.755). In the follow-up study, all the participants were >18 years old. We found a lower baseline ratio of IGF-1/IGFBP-3 in adolescence was an independent risk factor for MetS in adulthood (OR=10.724, 95% CI: 1.032-11.403) and also indicated a higher body mass index (beta=-1.361, 95% CI: -2.513 to -0.208) after 5 years. Conclusion: The lower IGF-1/IGFBP-3 ratio was an independent risk factor for MetS, hypertension, and high LDL-C in adolescents of northeast China and was also a predictive marker for MetS and increased body mass index in the adulthood.