Objective: This study intends to study the association between serum retinol binding protein 4 (RBP4), bone mineral density (BMD) and other bone metabolic-related parameters in type 2 diabetic patients older than 50 years, with or without osteopenia or osteoporosis.
Methods: Patients (n = 274 cases) with type 2 diabetes, hospitalized in the Endocrinology Department of Yantai Yuhuangding Hospital from December 2015 to March 2017, were enrolled in the study. The bone mineral density (BMD) was recorded by the dual-energy X-ray absorptiometer, and patients were divided into normal bone mineral density (148 cases), osteopenia (93 cases) and osteoporosis (33 cases) groups. The serum adipokine RBP4 and other biomarkers were determined accordingly.
Results: Serum RBP4, body weight, calcium and body mass index (BMI) demonstrated a positive correlation with BMD at all tested body sites in osteopenia and osteoporosis groups compared with normal bone mineral density group. In contrast, age, duration of diabetes and alkaline phosphatase (ALP) were inversely correlated with BMD at all tested body sites. In nonadjusted analyses, age, gender, duration of diabetes and ALP were inversely associated with BMD at the femoral neck, total hip and lumbar spine, while body weight, BMI and RBP4 were positively associated with BMD at all sites. In multiple regression analyses, adjusted for age, weight, BMI and other bone-related factors, a graded stepwise positive association between serum RBP4 and BMD was shown, at all sites.
Conclusion: Serum RBP4 was positively associated with BMD at all sites after adjustments for other factors in osteopenia and osteoporosis groups compared with normal bone mineral density group of type 2 diabetic patients.
Keywords: RBP4; alkaline phosphatase; body mass index; bone mineral density; retinol binding protein 4; type 2 diabetes mellitus.
© 2018 John Wiley & Sons Ltd.