Glucose Metabolism Effects of Vitamin D in Prediabetes: The VitDmet Randomized Placebo-Controlled Supplementation Study

Study answer

What this study found

Vitamin D3 clearly increased circulating 25(OH)D3 and lowered PTH, but it did not meaningfully improve glucose metabolism in this prediabetic population. Change in 120 min glucose differed across groups (placebo -0.5 [1.6], 40 μg/day 0.7 [1.7], 80 μg/day 0.5 [1.8]; P_K-W 0.039), but fasting glucose, fasting insulin, HbA1c, HOMA2 indices, and insulin sensitivity were not materially improved. A borderline reduction in IL-1 receptor antagonist suggested a possible modest anti-inflammatory effect, consistent with the authors' conclusion that wintertime high-dose vitamin D3 did not enhance…

Study & population

Randomized, placebo-controlled, three-arm supplementation study in older overweight adults with prediabetes from eastern Finland.

Intervention

Oral vitamin D3 was given daily for 5 months at two doses: 40 μg/day (1,600 IU/day) or 80 μg/day (3,200 IU/day).

Key limitation

Small active-arm sample sizes and a short 5-month duration limit power to detect modest metabolic effects.

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Original abstract