Effect of folic acid supplementation on homocysteine, serum total antioxidant capacity, and malondialdehyde in patients with type 2 diabetes mellitus.

Objective: Metformin is widely used in patients with type 2 diabetes, but it may decrease vitamin B12 and folate levels and increase levels of homocysteine (Hcy). Hyperhomocysteinemia (HHC) and hyperglycemia induce oxidative stress in type 2 diabetes. Thus, this study was performed to determine the effects of folate supplementation on the concentration of homocysteine, total antioxidant capacity (TAC), and malondialdehyde (MDA).
Methods: This was a double-blind randomized controlled clinical trial. Sixty-eight men with type 2 diabetes participated in the study with written consent. Patients were divided randomly into 2 groups: folic acid 5 mg/d and placebo. All patients received the tablets for 8 weeks. Anthropometric and nutrient intake data were obtained from each patient. Baseline and eighth-week homocysteine, total antioxidant capacity, malondialdehyde, folate, and B12 levels were measured.
Results: After folate supplementation in the folic acid group, homocysteine was significantly decreased (15.1 ± 3.2 to 12.1 ± 3.1 μmol/L, p < 0.001) and folate and B12 levels were significantly increased (p < 0.001). A significant increase in total antioxidant capacity (0.96 ± 0.2 to 1.14 ± 0.3 mmol Fe2+/L, p < 0.001) and a significant decrease in malondialdehyde (2.6 ± 0.7 to 1.7 ± 0.2 μmol/L, p < 0.001) were observed in the folic acid group, whereas no significant changes occurred in the placebo group (p > 0.05).
Conclusion: Pharmacological doses of folate supplementation lowered plasma homocysteine and serum malondialdehyde levels and improved serum total antioxidant capacity and folate and B12 levels in patients with type 2 diabetes.