Vitamin D May Help Prevent Diabetes – Depending on Genetics
New analysis of a major clinical trial finds supplementation reduced diabetes risk in prediabetic adults with certain variations in the vitamin D receptor gene
Prediabetes is a condition marked by higher-than-normal blood sugar levels that often leads to type 2 diabetes. A new study finds that vitamin D may help delay or prevent that progression – but only in people with certain genetic variations.
The study, published today in JAMA Network Open, found that 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.
The researchers analysed data from the D2d study, a large, multi-site clinical trial that tested the effect of 4,000 units of vitamin D per day versus placebo in more than 2000 US 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.
The original trial did not find a significant reduction in diabetes risk across all participants.
“But the D2d results raised an important question: Could vitamin D still benefit some people?” said Bess Dawson-Hughes, M75, the study’s lead author and a senior scientist at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University. “Diabetes has so many serious complications that develop slowly over years. If 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.”
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’ risk of developing diabetes.
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. The researchers wondered whether genetic differences in this receptor might explain why some people benefited from vitamin D while others did not. The pancreas’s insulin-producing cells have vitamin D receptors, suggesting the vitamin may help influence insulin release and blood sugar control.
For the new study, Dawson-Hughes and her colleagues analysed genetic data from 2098 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. They then compared response rates by subgroups of patients sorted according to three common variations in the vitamin D receptor gene.
This analysis revealed that adults with the AA variation of the ApaI vitamin D receptor gene (about 30% of the study population) did not respond to daily treatment with a high dose of vitamin D, compared with placebo. 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.
“Our findings suggest we may eventually be able to identify which patients with prediabetes are most likely to benefit from additional vitamin D supplementation,” said Dawson-Hughes. “In principle, this could involve a single, relatively inexpensive genetic test.”
By Genevieve Rajewski
Source: Tufts University
