Assessment of Vitamin D receptor levels and some physiological and biochemical markers in T1DM and T2DM Patients

Background: Diabetes mellitus is an increasingly serious problem in global health, and both type 1 (T1DM) and type 2 (T2DM) diabetes are correlated to the dysfunction of vitamin D receptor (VDR) as well as oxidative stress. The objective of this study was to determine the levels of VDR and markers of antioxidant status in patients with T1DM and T2DM compared to healthy controls. 
Methods: A total of 90 participants were enrolled in this cross-sectional study and randomly allocated into three groups (n=30 each) with two disease groups, normal controls, T1DM patients and T2DM patients. Levels of serum VDR were evaluated by ELISA. Spectrophotometric methods were employed to evaluate oxidative stress indicators such as superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT) and malondialdehyde (MDA). Blood glucose (FBG, HbA1c) were used to assess glycemic parameters. 
Results: VDR levels were significantly lower in both T1DM (2.34 ± 0.52 ng/mL) and T2DM (2.89 ± 0.61 ng/mL) groups compared to controls (4.12 ± 0.73 ng/mL, p<0.001). Antioxidant enzymes (SOD, GPx, CAT) showed significant reduction in diabetic groups, while MDA levels were significantly elevated (T1DM: 8.76 ± 1.34 nmol/mL; T2DM: 7.92 ± 1.28 nmol/mL vs. controls: 3.45 ± 0.67 nmol/mL, p<0.001). There were significant negative correlations between VDR and HbA1c (r=-0.68, p<0.001) and MDA (r=-0.71, p<0.001), and positive correlations with antioxidant enzymes. 
Conclusion: Decreased VDR together with increased oxidative stress and reduced antioxidant defenses were associated in both types of diabetes (T1DM and T2DM). According to these findings VDR is significantly played on pathophysic of diabetes and might represent an approach to control the oxidative stress.