Association of VDR gene polymorphism with insulin resistance in diabetic patients

Abstract

Introduction: It has been reported that vitamin D deficiency may predispose individuals to glucose intolerance and type 2 diabetes mellitus. Since FokI variant of Vitamin D Receptor (VDR) associates with alteration of receptor function which affects the bioactivity of vitamin D, we aimed to evaluate the association of FokI variant of VDR with various glucose metabolism indices among patients with diabetes mellitus type 2 (T2DM).

Methods: In a case series study, we recruited 105 patients with T2DM according to ADA criteria. Age at diagnosis, BMI, FBS, lipid profile, insulin levels and HbA1C were measured. HOMA-IR was calculated as index of insulin resistance. VDR genotyping was performed using PCR-RFLP method.

Results: Of totally 105 diabetic patients (mean age 55±10 years), 79.4% were female. Frequency of FF, ff and Ff genotypes were 71.4, 5.7 and 22.8%, respectively. In patients with Ff and ff genotype, age at diabetes onset was lower, BMI>27 and poor-controlled conditions were more frequent compared with FF genotype. In patients with ff and Ff genotypes the prevalence of obesity was higher, age of onset was significantly lower, HbA1C was higher, HOMA-IR was higher and poor-control condition was more prevalent as compared to FF genotype (P=0.04). The odds ratio and relative risk for association of ff genotype with poor-controlled condition were 2.54 (CI 95%: 1.05 to 6.17) and 1.68 (CI 95%: 0.97 to 2.89), respectively.

Conclusion: Our findings showed that VDR polymorphism is associated with age at diagnosis and insulin resistance in patients with type 2 diabetes mellitus. 

Keywords: Vitamin D Receptor (VDR), Type 2 diabetes, Polymorphism, Insulin resistance