The findings, published in JAMA Network Open, come from a new analysis of data from the D2d study. That large, multi-site clinical trial tested 4,000 units of vitamin D per day versus placebo in more than 2,000 US adults with prediabetes. The original trial did not find a significant reduction in diabetes risk across all participants.
Investigators analyzed genetic data from 2,098 trial participants who consented to DNA testing and compared subgroups defined by three common variations in the vitamin D receptor (VDR) gene. They reported that adults with the AA variation of the ApaI VDR gene—about 30% of the study population—did not respond to the high-dose vitamin D, while adults with AC or CC variations had a significantly reduced risk when taking the supplement.
Overall, one reported result was a 19% lower risk of developing diabetes in the subgroup with certain VDR variations who took vitamin D. The authors caution that people should not take high doses without medical advice and that more research is needed to identify who could benefit.
Difficult words
- analysis — a detailed examination of information or data
- placebo — a fake treatment used to compare real medicine
- clinical trial — a research study that tests medical treatments
- prediabetes — a condition with higher than normal blood sugar
- variation — a small difference in genes or traitsvariations
- vitamin D receptor — a protein that binds vitamin D in cells
- consent — to give permission for something to happenconsented
- subgroup — a smaller group within a larger study populationsubgroups
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- If genetic testing shows you have a VDR variation that responds to vitamin D, would you consider taking supplements? Why or why not?
- What are advantages and disadvantages of giving high-dose vitamin D to people with prediabetes?
- How could researchers use subgroup results like these to improve future clinical trials?
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