RBP4 and polycystic ovary syndrome: In women with PCOS aged ≤30 years, levels of RBP4 were positively correlated with WHR (r = 0.193, P = 0.020) and triglyceride levels (r = 0.685, P = 0.001) and negatively correlated with fasting glucose levels (r = −0.252, P = 0.002) after BMI adjustment.