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?
Related articles
Gagandeep Kang on Vaccines, Surveillance and Child Health in India
Gagandeep Kang, a leading expert on enteric diseases, urges India to prepare tools to prevent viral outbreaks. She helped develop indigenous rotavirus vaccines, built surveillance networks and now works at the Gates Foundation.
Virtual diet and exercise program helps people with lymphoma
A study tested a virtual diet and exercise program for people getting chemotherapy for lymphoma. The program improved symptoms, attendance was high, and participants had better strength and physical performance during treatment.
Parents' Attitudes Linked to Binge Drinking and Greek Life
A study finds that parents who are more permissive about alcohol are linked to students joining fraternities or sororities and higher binge drinking during the first college year. Authors suggest parenting programs to reduce risk.
Nepal’s cement industry: growth, jobs and pollution
After the 2015 Gorkha earthquake, Nepal expanded cement production with large investments, especially from Chinese firms. By 2019 it became self-sufficient and started exports to India in July 2022, while social and environmental problems grew.