Retinol-binding protein 4 and insulin resistance are related to body fat in primary and secondary schoolchildren: the Ouro Preto study.

Purpose: Evidence suggests that plasma retinol-binding protein 4 (RBP4) and insulin resistance are related to body fat (BF). We aimed to assess the relationship between RBP4 and insulin resistance with obesity in a mixed (skin color) cohort of the Brazilian population.

Methods: A nested case-control study was conducted in 227 schoolchildren aged 7-14 years. Schoolchildren with a high BF percentage (% BF, ≥ 30 for girls and ≥ 25 for boys) were identified as the obese group (n = 137), and those with lower values were identified as the non-obese group (n = 90). Percentage of body fat (% BF) was determined by tetrapolar bioimpedance (Quantum II, RJL System), RBP4 by enzyme-linked immunosorbent assay (Immunology Consultants Laboratory), plasma fasting insulin by chemiluminescent immunoassay (Access(®) Immunoassay System) and insulin resistance by the homeostasis model insulin resistance (IR(HOMA)) index. Serum lipid profile and arterial blood pressure were evaluated.

Results: The significant independent risk factors associated with obesity were as follows: male sex, increased serum LDL-C, RBP4 and IR(HOMA). Among children with higher RBP4, the association with obesity increased significantly (from 3.1 to 8.5) in the presence of insulin resistance, when compared to higher RBP4 and non-insulin resistance.

Conclusion: IR(HOMA) and RBP4 showed significant associations with obesity and traditional CVD risk factors. They might therefore be used as a marker for CVD risk and have clinical implications in the development of comorbidities associated with obesity.