A randomised controlled trial evaluating the impact of targeted vitamin D supplementation on endothelial function in type 2 diabetes mellitus: The DIMENSION trial

Study answer

What this study found

Targeted vitamin D repletion raised 25(OH)D to the intended range but did not produce a statistically significant improvement in the primary endothelial function outcome after adjustment. Reactive hyperemia index increased within the vitamin D arm from 0.65 (0.42) to 0.73 (0.36), but the between-group result was not significant after adjustment (p = 0.07), despite an unadjusted p = 0.02. Mean 25(OH)D rose from 17.3 ± 5.2 ng/mL at baseline to 31.3 ± 9.0 ng/mL at 8 weeks and 31.6 ± 9.5 ng/mL at 16 weeks; 16/33 (49%) achieved >30 ng/mL at 8 weeks and 23/33 (70%) at 16 weeks. Other…

Study & population

Randomized, double-blind, placebo-controlled trial in adults with type 2 diabetes mellitus and hypovitaminosis D at a single tertiary centre in Singapore.

Intervention

In the active arm, participants received oral cholecalciferol for 16 weeks using a targeted dosing strategy based on baseline 25(OH)D: 4000 IU daily if baseline 25(OH)D was ≤20 ng/mL, or 2000 IU daily if baseline 25(OH)D was 21-30 ng/mL.

Key limitation

The trial was relatively small, single-centre, and short duration, which limits power to detect modest cardiovascular effects.

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Original abstract