The Correlation BetweenSerum Vitamin D Level and Total Antioxidant Capacity in Diabetic and Non-diabetic Subjectsin Iran

Background & objective: Increase in intra- and extracellular glucose levels can cause oxidative stress, and theprolonged imbalance between prooxidants and antioxidantscan lead to cell damage and the associated complications in patients with diabetes. Vitamin D acts as a strong antioxidant in the body and several studies emphasized on its important role to preventoxidative stress in prediabeticand diabetic subjects. The current study aimed at determining and comparingthe total antioxidant capacity (TAC) in individuals with hemoglobin A1c(HbA1c) below and above 6.5%, and its correlation with vitamin D levels. Methods: The current cross sectional study was conducted on a total of 107patients with diabetes (HbA1c >6.5%) and 107 non-diabetic subjects (HbA1c<6.5%)referred toRassoolAkram Hospital, Tehran, Iranfrom2015 to 2016, as the sample population. The two groups were compared regarding their TAC and vitamin D serum levels and the association between vitamin D concentration and TAC was evaluated. Results: Age and body mass index (BMI)were significantly higher in patients with diabetes,comparedwiththe serum levels of vitamin D and TAC (P<0.001 for both). Both TAC and vitamin D levels were significantly lower in the group with diabetesand a weak significant correlation was observedbetween the two factors (r=0.2, P=0.003). In multivariate regression model, the duration of diabetes was also significantly associated with TAC level (beta coefficient=-0.82, P <0.001). Conclusion: The low serum levels of TAC and vitamin D in patients with diabetescould be indicative of oxidative stress in the presence of high blood glucose levels. Supplementation of vitamin D in patients with diabetes might be effective to control thenegative impacts of the disease and decreasecells’ exposure to oxidative environment in prediabetes.