Beyond the D2d Primary Outcome

We continue to analyze study data to examine the effect of vitamin D supplementation on additional outcomes, including new onset cancer and cardiovascular disease. For a list of D2d publications, visit our publications page.

Visit Our D2d Publications Page
Draw your own conclusions

D2d is a large-scale NIH-supported trial to test whether vitamin D supplementation reduces diabetes risk in adults with prediabetes. The main results were published in the New England Journal of Medicine. Vitamin D supplementation did not significantly lower diabetes risk (hazard ratio 0.88; 95% CI 0.75 to 1.04). D2d and two other diabetes prevention trials (in Norway and Japan) among people at risk for diabetes have reported nearly identical results. We recently published a systematic review in this topic and we plan to combine results in an individual participant data meta-analysis.

D2d will define the natural history of diabetes

Currently, we do not know how large the risk of developing diabetes is among people with pre-diabetes, as defined the American Diabetes Association criteria. Some researchers think that we need to screen for pre-diabetes and intervene to keep glucose levels as normal as possible. Others advocate that the current definitions of pre-diabetes risk unnecessary medicalization and create unsustainable burdens for health care systems. D2d will define the natural history of diabetes and, as such, will reconcile these two opposing views.

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D2d has Completed Recruitment

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 met its enrollment target on December 16, 2016.

D2d will define the natural history of diabetes

Currently, we do not know how large the risk of developing diabetes is among people with pre-diabetes, as defined the American Diabetes Association criteria. Some researchers think that we need to screen for pre-diabetes and intervene to keep glucose levels as normal as possible. Others advocate that the current definitions of pre-diabetes risk unnecessary medicalization and create unsustainable burdens for health care systems. D2d will define the natural history of diabetes and, as such, will reconcile these two opposing views.

D2d Study Registry

The Registry provides information to you about future research opportunities related to the D2d study. If you are interested, please clink the link to sign up online.

Signing up for the D2d Registry does not mean you are committing to any future research studies — it simply allows Dr. Pittas (the study’s principal investigator) at Tufts Medical Center to inform you about future follow-up studies to D2d that are currently being planned. Your information in the D2d Registry will be kept confidential by Dr. Pittas’ research team. If you change your mind and would like to remove your name from the Registry, you can do so at any time by contacting Dr. Pittas’ research team.

d2dos@tuftsmedicalcenter.org

617-636-3232

US States
Represented

Enrolled

Continue in D2d

Mean Age

Women

Over 2400 dedicated participants have joined D2d

We love our participants and we are fully committed to them

“I would encourage others to join D2d for opportunities to learn about type 2 diabetes.”

“The staff is terrific. I’ve learned so much about preventing diabetes.”

“I appreciate the people that I deal with.”

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.

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