Objective: To determine the relation between serum concentration of retinol binding protein (RBP) 4 and markers of bone metabolism, bone mineral density (BMD) in patients with type 2 diabetes mellitus (T2DM).
Methods: A total of 82 patients newly diagnosed with T2DM and 46 subjects with normal glucose tolerance (NGT) enrolled in the cross-sectional study. Subset analyses were performed, dividing subjects on the basis of gender into M-T2DM, F-T2DM, M-NGT, and F-NGT. The serum concentrions of RBP4, osteocalcin (OC) and C-terminal telopeptide of collagen type I (CTX) were measured with ELISA. The BMD was measured by dual-energy X-ray absorptiometry (DXA) with a Hologic QDR4500A device.
Results: In both the T2DM groups, lnRBP4 showed a positive relationship with lnCTX (M-T2DM, r=0.564, P<0.01; F-T2DM, r=0.386, P=0.018), but no association with lnOC. After adjusting for age, smoking, creatinine clearance rate (CCr), and waist-to-hip ratio (WHR), lnRBP4 still showed a strong association with lnCTX in the M-T2DM group (r'=0.536, P<0.01), but not in F-T2DM (r'=0.317, P=0.072). In the NGT group, there was no relation between lnRBP4 and lnCTX or lnOC. LnRBP4 showed no association with BMD in all groups.
Conclusion: The level of serum RBP4 may be correlated with the bone metabolism in patients with T2DM.