Investigation of the Relationship Between Retinol Binding Protein 4, Metabolic Syndrome and Insulin Resistance in Iranian Obese 5-17 Year Old Children

Objective: Retinol-binding protein 4 (RBP4) has recently been reported to be associated with insulin resistance (IR) and the metabolic syndrome by a number of researchers in various populations. However, controversies are present among different studies, which might be due to the differences between various ethnic, age, and sex groups. This study aimed to determine whether RBP4 can be assumed as a marker of IR and the metabolic syndrome in the Iranian obese children.
Methods: In the present longitudinal cross-sectional study, 100 5-17 years old obese children were recruited from January 1, 2011 to February 1, 2012. The patients’ information including the demographic variables, health status and behavior, and daily physical activity were collected. Moreover, serum RBP4 was measured and correlated with the homeostasis model assessment of IR index (HOMA-IR), components of the metabolic syndrome, and lipoprotein metabolism.
Findings: The results revealed a positively significant correlation between RBP4 and the HOMA-IR index (P=0.02). Partial Spearman test also revealed a significant correlation between RBP4 plasma concentrations and the components of the metabolic syndrome, including waist circumference, systolic (but not diastolic) blood-pressure, and fasting blood sugar (P<0.05). However, no significant correlation was observed between RBP4 and HDL (P=0.3) as well as triglycerides concentration (P=0.1). Moreover, plasma RBP4 level gradually increased with the increasing number of the metabolic syndrome components.
Conclusion: Regarding the results of the present study and previous investigations, RBP4 seems to be a suggestible predictive marker for both insulin resistance and metabolic syndrome in Iranian obese children; however, further studies are needed to be conducted among different ethnicities and age groups in order to determine the predictive value of this correlation.

Keywords
Retinol Binding Protein 4; Insulin Resistance; Metabolic Syndrome; Obesity; Children