Effect of folate supplementation on insulin sensitivity and type 2 diabetes: a meta-analysis of randomized controlled trials.

Study answer

What this study found

Folate supplementation improved insulin sensitivity markers but did not meaningfully change fasting glucose, HbA1c, or type 2 diabetes incidence overall. Pooled effects favored folate for fasting insulin (WMD -13.47 pmol/L; 95% CI -21.41, -5.53; P < 0.001) and HOMA-IR (WMD -0.57; 95% CI -0.76, -0.37; P < 0.001), while fasting glucose was unchanged (WMD -0.02 mmol/L; 95% CI -0.06, 0.02; P = 0.43) and HbA1c was unchanged (WMD -0.06%; 95% CI -0.24, 0.12; P = 0.34). For type 2 diabetes development, the pooled RR was 0.91 (95% CI 0.80, 1.04; P = 0.16), so evidence was insufficient to conclude a…

Study & population

Systematic review and meta-analysis of 29 randomized controlled trials including 22,250 adults older than 18 years.

Intervention

Across the included randomized trials, folate was given orally as folic acid or 5-methyltetrahydrofolate, typically once daily, for durations ranging from weeks to years.

Key limitation

The evidence base was heterogeneous in participant health status, folate form, dose, duration, and co-supplementation, which limits direct comparability across trials.

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Original abstract