Serum RBP4 positively correlates with triglyceride level but not with BMI, fat mass and insulin resistance in healthy obese and non-obese individuals

Purpose: Retinol binding protein 4 (RBP4) has recently been identified as an adipokine possibly involved in the development of impaired glucose metabolism. We aimed to test serum RBP4 in healthy non-obese individuals and in patients with well-characterized phenotype: obesity without confounding effects of diabetes, metabolic syndrome or dyslipidaemia. Additionally, we examined whether serum RBP4 is associated with anthropometric parameters, insulin resistance and blood lipid parameters. Patients and methods: Twenty-eight patients with obesity and no co-morbidities and twenty-five age-matched lean controls were recruited. Anthropometric parameters, body composition, fasting blood lipid profile, RBP4, glucose and insulin were assessed and HOMA-IR was calculated. Results: Mean concentration of RBP4 did not differ between studied groups (in obese patients was 33.9 +/- 34.46 mu g/ml and 32.53 +/- 2.53 mu g/ml in non-obese controls). RBP4 positively correlated with serum triglycerides in obese and non-obese individuals (r = 0.74, p = 0.03 and r = 0.62, p = 0.02, respectively) and did not show any significant associations with HOMA-IR, anthropometric and body composition parameters. Conclusions: Excessive adiposity without co-morbidities is not associated with higher levels of circulating RBP4. Serum RBP4 cannot be considered as a direct predictive marker for impaired glucose metabolism. RBP4 possibly contributes to lipid metabolism.