Pittas AG, Dawson-Hughes B, Sheehan P, et al. – In this study, researchers examined whether the risk of diabetes lowers with vitamin D supplementation. Overall, outcomes revealed no significantly lower risk of diabetes in correlation with vitamin D₃ supplementation at a dose of 4,000 IU per day vs placebo among individuals at high risk for type 2 diabetes who were not vitamin D insufficient.

Methods

• Researchers randomized 2,423 adults—who met at least two of three glycemic criteria for prediabetes and no criteria for diabetes—to receive either 4,000 IU per day of vitamin D3 (n = 1,211) or placebo (n = 1,212), regardless of the baseline serum 25-hydroxyvitamin D level.
• New-onset diabetes was the primary outcome in this analysis, and the trial design was event-driven. A total of 508 was the target number of diabetes events.

Results

• Participants in the vitamin D group had mean serum 25-hydroxyvitamin D levels of 54.3 ng per milliliter (from 27.7 ng per milliliter at baseline) vs 28.8 ng per milliliter in participants in the placebo group (from 28.2 ng per milliliter at baseline) by month 24.
• A total of 293 participants in the vitamin D group and 323 in the placebo group developed diabetes after a median follow-up of 2.5 years (9.39 and 10.66 events per 100 person-years, respectively).
• For vitamin D vs placebo, an HR of 0.88 was reported (95% CI: 0.75-1.04; P = 0.12).
• The two groups did not differ significantly in terms of the incidence of adverse events.