Antioxidant effects of vitamins in type 2 diabetes: a meta-analysis of randomized controlled trials

What this study found

Overall, vitamin supplementation had favorable effects on antioxidant status in type 2 diabetes, although results were heterogeneous and not uniform across all vitamins. Pooled analyses showed increased GPx (MD 9.40, 95% CI 7.79 to 11.00), reduced MDA (MD -0.53, 95% CI -0.81 to -0.25), reduced TBARS (SMD -4.84, 95% CI -6.01 to -3.67), increased TAC (SMD 0.38, 95% CI 0.11 to 0.65), and increased SOD (SMD 0.64, 95% CI 0.11 to 1.17). Vitamin E also improved glycemic outcomes versus placebo, with lower blood glucose (MD -13.89, 95% CI -19.89 to -7.89) and HbA1c (MD -0.47, 95% CI -0.69 to -0.26).

Study & population

Systematic review and meta-analysis of randomized controlled trials in adults with type 2 diabetes from multiple countries.

Intervention

Randomized trials tested vitamin supplementation versus placebo or control in adults with type 2 diabetes, with regimens spanning vitamin B9 5 mg/day, vitamin C 800 to 2000 mg/day, vitamin D 2000 to 40000 IU/week or 4000 IU/day, vitamin E 400 to 800 IU/day, and a vitamin complex containing B, C, and E.

Key limitation

The evidence base was limited by substantial heterogeneity across trials, including wide variation in vitamin type, dose, formulation, duration, and outcomes.

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