![\"Dawson-Hughes](\"https:\/\/www.newsbeep.com\/nz\/wp-content\/uploads\/2026\/04\/image_4624-Vitamin-D.jpg\")
<\/p>\nIn a large clinical trial, Tufts University researcher Bess Dawson-Hughes and colleagues found that vitamin D supplements reduced diabetes risk only in people with certain genetic variants, pointing toward a more personalized approach to prevention.<\/p>\n
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Dawson-Hughes et al. found prediabetic adults with certain variations in the vitamin D receptor gene had a 19% lower risk of developing diabetes when taking a high daily dose of vitamin D.<\/p>\n
Dr. Dawson-Hughes and co-authors analyzed data from the D2d study, a multisite randomized, double-blind, placebo-controlled clinical trial conducted from October 1, 2013, to November 28, 2018.<\/p>\n
The original trial tested the effect of 4,000 units of vitamin D per day versus placebo in more than 2,000 U.S. adults with prediabetes to see if a daily high dose of vitamin D would lower the chance of these particularly high-risk individuals developing diabetes.<\/p>\n
However, it did not find a significant reduction in diabetes risk across all participants.<\/p>\n
\u201cBut the D2d results raised an important question: could vitamin D still benefit some people?\u201d Dr. Dawson-Hughes said.<\/p>\n
\u201cDiabetes has so many serious complications that develop slowly over years.\u201d<\/p>\n
\u201cIf we can delay the time period that an individual will spend living with diabetes, we can stop some of those harmful side effects or lessen their severity.\u201d<\/p>\n
Through an earlier analysis, the D2d research team found that blood levels of 40 to 50 ng\/mL of 25-hydroxyvitamin D or higher were linked to substantial and progressively larger reductions in participants\u2019 risk of developing diabetes.<\/p>\n
Vitamin D circulating in the blood is converted into its active form in the body before binding to the vitamin D receptor, a protein that helps cells respond to the vitamin.<\/p>\n
The researchers wondered whether genetic differences in this receptor might explain why some people benefited from vitamin D while others did not.<\/p>\n
The pancreas\u2019 insulin-producing cells have vitamin D receptors, suggesting the vitamin may help influence insulin release and blood sugar control.<\/p>\n
For their new study, the scientists analyzed genetic data from 2,098 trial participants who had consented to DNA testing according to two groups: participants who appeared to benefit from vitamin D supplementation and those who did not.<\/p>\n
They then compared response rates by subgroups of patients sorted according to three common variations in the vitamin D receptor gene.<\/p>\n
This analysis revealed that adults with the AA variation of the ApaI vitamin D receptor gene \u2014 about 30% of the study population \u2014 did not respond to daily treatment with a high dose of vitamin D, compared with placebo.<\/p>\n
In contrast, the analysis found that the same treatment in adults with the AC or CC variations of the vitamin D receptor gene saw a significantly reduced risk of developing diabetes compared with those taking a placebo.<\/p>\n
\u201cThe findings may represent an important step toward developing a personalized approach to lowering the risk of developing type 2 diabetes among high-risk adults,\u201d said Tufts University School of Medicine\u2019s Professor Anastassios Pittas.<\/p>\n
\u201cPart of what makes vitamin D appealing as a potential preventive tool is that it is inexpensive, widely available, and easy for people to take.\u201d<\/p>\n
The authors cautioned that the findings do not mean people should start taking high doses of vitamin D on their own to prevent diabetes.<\/p>\n
Current guidelines recommend 600 IU per day for people ages 1 to 70 and 800 IU per day for those older than 70.<\/p>\n
Taking too much vitamin D can be harmful and has been linked to an increased risk of falls and fractures in older adults.<\/p>\n
More research is needed to better understand which individuals might benefit from a higher daily dose.<\/p>\n
\u201cOur findings suggest we may eventually be able to identify which patients with prediabetes are most likely to benefit from additional vitamin D supplementation,\u201d Dr. Dawson-Hughes said.<\/p>\n
\u201cIn principle, this could involve a single, relatively inexpensive genetic test.\u201d<\/p>\n