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Vitamin D and the Risk for Type 2 Diabetes in People With Prediabetes
TAKE-HOME MESSAGE
- In this systematic review and meta-analysis, the authors assessed whether vitamin D administration decreases the risk for diabetes in individuals with prediabetes. Combining data from three randomized trials, the authors demonstrated that vitamin D reduced the risk of diabetes by 15% and increased the likelihood of regression to normal glucose regulation.
- Vitamin D may be effective in decreasing the risk for diabetes in adults with prediabetes.
abstract
This abstract is available on the publisher's site.
Access this abstract nowBACKGROUND
The role of vitamin D in people who are at risk for type 2 diabetes remains unclear.
PURPOSE
To evaluate whether administration of vitamin D decreases risk for diabetes among people with prediabetes.
DATA SOURCES
PubMed, Embase, and ClinicalTrials.gov from database inception through 9 December 2022.
STUDY SELECTION
Eligible trials that were specifically designed and conducted to test the effects of oral vitamin D versus placebo on new-onset diabetes in adults with prediabetes.
DATA EXTRACTION
The primary outcome was time to event for new-onset diabetes. Secondary outcomes were regression to normal glucose regulation and adverse events. Prespecified analyses (both unadjusted and adjusted for key baseline variables) were conducted according to the intention-to-treat principle.
DATA SYNTHESIS
Three randomized trials were included, which tested cholecalciferol, 20 000 IU (500 mcg) weekly; cholecalciferol, 4000 IU (100 mcg) daily; or eldecalcitol, 0.75 mcg daily, versus matching placebos. Trials were at low risk of bias. Vitamin D reduced risk for diabetes by 15% (hazard ratio, 0.85 [95% CI, 0.75 to 0.96]) in adjusted analyses, with a 3-year absolute risk reduction of 3.3% (CI, 0.6% to 6.0%). The effect of vitamin D did not differ in prespecified subgroups. Among participants assigned to the vitamin D group who maintained an intratrial mean serum 25-hydroxyvitamin D level of at least 125 nmol/L (≥50 ng/mL) compared with 50 to 74 nmol/L (20 to 29 ng/mL) during follow-up, cholecalciferol reduced risk for diabetes by 76% (hazard ratio, 0.24 [CI, 0.16 to 0.36]), with a 3-year absolute risk reduction of 18.1% (CI, 11.7% to 24.6%). Vitamin D increased the likelihood of regression to normal glucose regulation by 30% (rate ratio, 1.30 [CI, 1.16 to 1.46]). There was no evidence of difference in the rate ratios for adverse events (kidney stones: 1.17 [CI, 0.69 to 1.99]; hypercalcemia: 2.34 [CI, 0.83 to 6.66]; hypercalciuria: 1.65 [CI, 0.83 to 3.28]; death: 0.85 [CI, 0.31 to 2.36]).
LIMITATIONS
Studies of people with prediabetes do not apply to the general population. Trials may not have been powered for safety outcomes.
CONCLUSION
In adults with prediabetes, vitamin D was effective in decreasing risk for diabetes.
PRIMARY FUNDING SOURCE
None. (PROSPERO: CRD42020163522).
Additional Info
Disclosure statements are available on the authors' profiles:
Vitamin D and Risk for Type 2 Diabetes in People With Prediabetes : A Systematic Review and Meta-analysis of Individual Participant Data From 3 Randomized Clinical Trials
Ann. Intern. Med 2023 Feb 07;[EPub Ahead of Print], AG Pittas, T Kawahara, R Jorde, B Dawson-Hughes, EM Vickery, E Angellotti, J Nelson, TA Trikalinos, EM BalkFrom MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
Vitamin D for prediabetes
Every vitamin has had its brush with greatness, attracting the eye of research only to return to its place of balance, far from being a “cure all.” Vitamin D is more a hormone than a vitamin and this meta-analysis of three large studies shows promise in helping prevent the progression from prediabetes to diabetes.
There was a 15% relative risk reduction (RR) in patients using vitamin D supplementation compared with those who did not. To put this into perspective, the Diabetes Prevention Program Study showed a 58% RR reduction with aggressive lifestyle modification (averaging 8 lbs of weight loss) and a 31% RR reduction with the use of metformin. This study showed that only 30 patients with prediabetes would need to be treated with vitamin D to prevent one case from progressing to diabetes (number needed to treat [NNT] of 30). The NNT in the Diabetes Prevention Program for lifestyle modification was 7 and the NNT for metformin was 14.1
Clinical pearls from this study
Take home
For your patients with prediabetes, consider checking 25-hydroxy vitamin D levels and supplement to get levels between 50 to 60 ng/mL (125–150 nmol/L).
Vitamin D is not a cure all. However, it may be another useful tool in preventing metabolic dysfunction. Most importantly, encourage patients to go outside and get non-burning sun exposure to raise their vitamin D levels while exercising and enjoying nature. That is good for the body, mind, and soul.
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