Objective: It is known that markers of oxidative stress and nitrite/nitrate anion (NOx) increase and activity of antioxidative enzyme paraoxonase-1 decline in type 2 diabetes mellitus (DM). The effects of vitamin E on paraoxonase-1 activity and NOx in patients with type 2 diabetes are not known. The purpose of this study was to examine the hypothesis that vitamin E supplementation would affect paraoxonase-1 activity, metabolic factors, and NOx in patients with DM.
Methods: This double-blind, randomized, controlled clinical trial was conducted on 83 patients with DM aged 30-60 years. Forty-two of the subjects had taken 400 IU/day vitamin E and 41 were given placebo over 8 weeks. Fasting blood samples, anthropometric measurements, and dietary intake data were collected at the baseline and at the end of the trial.
Results: Vitamin E significantly increased serum vitamin E level, paraoxonase-1 activity, and total antioxidant status (TAS) and decreased fasting blood sugar (FBS) compared to the control group (p < 0.05). Hemoglobin A1c, serum insulin, and insulin resistance significantly decreased in the vitamin E group compared to baseline values (p < 0.05). Alterations in serum levels of malondialdehyde and NOx were not significant in any of groups (p > 0.05).
Conclusions: Vitamin E improved serum vitamin E level, paraoxonase-1 activity, TAS, and FBS in patients with type 2 diabetes. Longitudinal studies are warranted to assess the outcome of these results in reducing complications of diabetes in patients with type 2 diabetes.
Keywords: metabolic factors; nitrite/nitrate anion; paraoxonase-1; type 2 diabetes; vitamin E.