High-Dose Vitamin D Supplements May Reduce Diabetes Risk By 19% In Genetically Predisposed Adults: Study

Prediabetes affects 15.3% of India's population, which is nearly 136 million people, according to a ICMR-INDIAB study. India ranks second globally for diabetes burden. If appropriate measures are not taken, prediabetes can lead to type 2 diabetes. If you have high blood sugar levels persistently, it can lead to heart disease, nerve damage, and vision loss, among others. Now, a new study found that high-dose vitamin D supplements show promise in reducing diabetes risk for certain adults. The study highlights how genetics play a key role in this benefit.

The new study was published in JAMA Network Open and was conducted by researchers from Tufts University. The team reanalysed data from the D2d trial. That large study involved adults who took either 4,000 IU of vitamin D daily or a placebo for about 2.5 years. While the original D2d results didn't show any drop in overall diabetes risk across all participants, the new study revealed targeted benefits.

Study Details and Methods

Researchers from Tufts University tested DNA from 2,098 D2d participants who agreed to genetic checks. They grouped people by three common VDR gene variants and compared diabetes rates in vitamin D versus placebo arms. Diabetes was confirmed by blood tests showing fasting glucose over 126 mg/dL, two-hour glucose over 200 mg/dL, or HbA1c above 6.5%. The trial was done across multiple US sites.

Study Findings

The study found that adults with specific variations in the vitamin D receptor (VDR) gene, AC or CC types at the ApaI spot, could cut their diabetes risk by 19% with high-dose vitamin D compared to placebo. About 70% of people carry these variants, making the effect widespread among people with prediabetes. Those with the AA variant (around 30%) saw no benefit.

Anastassios Pittas, the study's senior author, a professor of medicine at Tufts University School of Medicine, and chief of endocrinology, diabetes, and metabolism at Tufts Medical Center, said, "The findings may represent an important step toward developing a personalized approach to lowering the risk of developing type 2 diabetes among high-risk adults. Part of what makes vitamin D appealing as a potential preventive tool is that it is inexpensive, widely available, and easy for people to take."

How Vitamin D Works in the Body

Vitamin D helps the cells respond to insulin, the hormone that controls blood sugar. In the pancreas, where insulin is made, cells have VDR proteins that bind active vitamin D. Genetic tweaks in VDR can change how well this binding happens, explaining why supplements help some but not others.

High doses raised blood vitamin D levels to 40-50 ng/mL or higher, linked to higher risk cuts in earlier D2d analysis. Normal guidelines suggest just 600-800 IU daily, so 4,000 IU is much higher but safe in the trial with no extra side effects like falls or fractures. However, the authors cautioned against taking high doses of vitamin D on their own to prevent diabetes.

Bess Dawson-Hughes, study's lead author and senior scientist at the Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, said, "Our findings suggest we may eventually be able to identify which patients with prediabetes are most likely to benefit from additional vitamin D supplementation. In principle, this could involve a single, relatively inexpensive genetic test."

Personalised medicine helps to tailor treatments to your genes. Dawson-Hughes noted it could delay diabetes onset, reducing its impact in the long-term.

Practical Advice and Cautions

Don't self-dose high vitamin D yet as overdoing it can increase the risk of toxicity. It is important that you talk to your doctor, especially if you have prediabetics.

Lifestyle is the most important. Eat a balanced diet, perform some physical activity like yoga, and maintain your body weight. For genetically prone adults, this study offers hope, vitamin D might provide a simple shield.

Disclaimer: This content including advice provides generic information only. It is in no way a substitute for a qualified medical opinion. Always consult a specialist or your own doctor for more information. NDTV does not claim responsibility for this information.