Big effect
Vitamin D supplementation linked to a 0.60 drop in insulin in a meta-analysis — but only in people with fatty liver disease.
The finding is based on three randomized trials, all pointing in the same direction, making the evidence moderately reliable — but it only applies to patients with metabolic-associated fatty liver disease, not to healthy individuals.
A meta-analysis of three clinical trials found that vitamin D supplementation reduced insulin levels by 0.60 units in people with fatty liver disease, suggesting better blood sugar control. The same analysis also found improvements in fasting glucose, triglycerides, and HDL cholesterol, but no significant changes in total or LDL cholesterol. Because the studies only enrolled patients with fatty liver, the results may not apply to people without that condition.
Where this fits in the evidence
Pillser has synthesized 3 studies on Vitamin D for Improved Insulin Levels — overall evidence strength: Moderate.
Across all 3 studies, vitamin D supplementation showed beneficial effects on insulin levels, with moderate-sized effects observed in two studies and a small effect in one meta-analysis. The evidence includes a randomized controlled trial in 60 women with gestational diabetes mellitus (1000 IU/day for 42 days), which reported a significant reduction in serum insulin, and two meta-analyses in type 2 diabetes and MAFLD populations showing significant pooled reductions. Effects were typically observed at approximately 6 weeks of supplementation, though study durations were limited.
The study
- Meta-Analysis
- 2026-04
- The Journal of nutrition
This is a plain-language summary of a research finding, not medical advice. Pillser surfaces research signals to help you decide what's worth investigating — always consult a qualified professional before changing what you take.