Association of Vitamin D receptor (TaqI, BsmI, and FokI) polymorphisms with prediabetes and Type 2 diabetes in Asian Indians

Abstract

Background: Vitamin D deficiency is known to be involved in the development of insulin resistance and type 2 diabetes (T2D), and the functions of Vitamin D are mediated through Vitamin D receptor (VDR). Only a few reports are available in the Asian Indian population highlighting the role of VDR polymorphism in diabetes. We aimed to investigate the association of VDR gene polymorphisms (TaqI, BsmI and FokI) with prediabetes (PD) and T2D and their relationship with anthropometric and biochemical parameters in Asian Indians. Subjects and Methods: In this study, 454 participants including 147 with normal glucose tolerance (NGT), 145 with PD, and 162 with T2D were enrolled in this study. Genetic variants of the VDR were genotyped using polymerase chain reaction-restriction fragment length polymorphism method. Anthropometric measurements were done in all participants. Results: The most common genotypes for TaqI, BsmI, and FokI were TC, GA, and CC, respectively. The allele distribution of TaqI differed significantly when compared between NGT and T2D group. A significant protection was shown against T2 in VDR TaqI genotypes after adjusting for age, gender, and Body Mass Index. The levels of homeostatic model assessment for insulin resistance, fasting insulin, and the waist-hip ratio were significantly higher in TT genotype when compared with TC + CC genotype of TaqI polymorphism in NGT. In PD group, the levels of serum cholesterol and low-density lipoprotein cholesterol were significantly higher in AA genotype when compared with GA + GG genotype in BsmI polymorphism. Conclusions: The study indicates VDR TaqI, and BsmI polymorphisms seem to influence anthropometric and biochemical parameters, and in particular, VDR TaqI polymorphism offers protection against T2D in Asian Indians.