Association of Vitamin D Receptor gene polymorphisms with the occurrence of low bone density, osteopenia, and osteoporosis in patients with type 2 diabetes

Abstract Background Diabetes, osteoporosis, and Vitamin D deficiency are interrelated. The association of the Vitamin D receptor (VDR) gene with bone density is not established in different populations. This study analyze the association between five VDR gene polymorphisms (Fok1 (rs2228570), Taq1 (rs731236), Bsm1 (rs1544410), Apa1 (rs7975232), and EcoRV (rs4516035)) and the occurrence of low bone density (LBD)/osteopenia/osteoporosis in Iranian type 2 diabetics (T2D).Methods This study contained 165 patients with T2D. Separated for gender and polymorphism, crude and adjusted (for age and BMI), logistic regression analysis provided odds ratios (ORs). The most common haplotype was used as the reference for each type of VDR gene polymorphism.Results The occurrence of T2D was 13.03% (165/1266) for the people dwelling in the city of Sanandaj in 2012, until 2013. 13.92% and 81.29% of participants with T2D had osteoporosis and vitamin D deficiency, respectively. In women, tt genotype significantly decreased the risk of LBD/osteopenia/osteoporosis versus Tt genotype, after adjusting for BMI and age (OR=0.18, CI: 0.03-0.97). Conversely, the EE genotype increased the risk of LBD/osteopenia/osteoporosis versus Ee genotype (OR=7.64, CI: 2.03-28.72).Conclusions Among the patients with T2D, Vitamin D deficiency and osteoporosis were prevalent, and some genetic variations in VDR were significantly associated with osteoporosis. In women, a weak protective role in LBD/osteopenia/osteoporosis was found for tt variant of TaqI polymorphism. More importantly, EE variant of EcoRV polymorphism had a strong significant association with increasing the risk of LBD/osteopenia/osteoporosis. Further ethnicity-based cohort studies based on a large study group of T2D patients are recommended.