D2d Study is Under Way

D2d is a large-scale clinical trial to investigate if vitamin D supplementation helps prevent or delay type 2 diabetes in adults who are at high risk for diabetes (pre-diabetes). "Past observational studies have suggested that higher levels of vitamin D may be beneficial in preventing type 2 diabetes, but until the D2d study is complete, we won’t know if taking vitamin D supplements lowers the risk of diabetes,” said Anastassios G. Pittas, M.D., M.S., the study’s principal investigator. The D2d study is funded by the National Institutes of Health and taking place in 22 cities across the United States.


Are You at Risk for Diabetes

86 million Americans have pre-diabetes (1/3 of the adult population) and their chance of developing diabetes is about 10% per year. Physical activity and weight loss can lower diabetes risk. However, many people still develop diabetes despite efforts at changing their lifestyle.

Click for information on pre-diabetes.

Participate & Spread the Word

To see if you are at risk for diabetes and whether you qualify for D2d, click here.

Know someone, a friend or family member, who might be interested in joining D2d as a participant? You can easily share with others by email or on social media.
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Over 2300 dedicated participants have joined D2d

We love our participants and we are fully committed to them

D2d is a nationwide study

D2d takes place in 22 medical centers across the United States. Approximately 35% of the US population lives within the larger metropolitan areas covered by the D2d sites.

D2d | Division of Endocrinology, Diabetes and Metabolism | Tufts Medical Center | Boston MA
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