More than 84 million Americans are at an increased risk of developing type 2 diabetes in adulthood. During recent years, low blood levels of vitamin D have surfaced as a potential risk factor for type 2 diabetes. However, until recently it was unclear whether vitamin D supplementation could help prevent type 2 diabetes. A group of researchers in the United States, working on the D2d (Vitamin D and Type 2 Diabetes) study, just published the results of a randomized placebo-controlled clinical trial that helps answer this question.

As part of the D2d study, researchers tracked 2,423 pre-diabetic patients, who received either 4000 IU (International Units) per day of vitamin D3 or a placebo for approximately 2.5 years. They found that vitamin D3 supplementation at the administered dose did not result in a significantly lower risk of a participant developing diabetes, compared to those participants who took the placebo. 

So while type 2 diabetes actually may not be prevented by vitamin D supplementation, persons at high risk for type 2 diabetes who are overweight or obese can still prevent or slow the progression to diabetes by incorporating lifestyle changes such as weight loss and physical activity.