Results from the Vitamin D and Type 2 Diabetes (D2d) Study, a multicenter randomized controlled trial for diabetes prevention, will be presented at 11:30 a.m. Friday in S-157 (South, Upper Level Mezzanine). ADAMeetingNews.org asked the study’s principal investigator, Anastassios G. Pittas, MD, MS, to discuss the background, objective, and the significance of the study. Dr. Pittas is Co-Director of the Diabetes and Lipid Center at Tufts Medical Center and Professor of Medicine at Tufts University School of Medicine.
Dr. Pittas: Vitamin D insufficiency has emerged as a potential key contributor to the pathophysiology of type 2 diabetes. Observational studies consistently report an inverse association between blood 25-hydroxyvitamin D (25[OH]D) concentration and incident diabetes. However, whether vitamin D supplementation lowers risk of diabetes is unknown. This is an important question because more than 84 million Americans are at high risk of developing diabetes and the prevalence of diabetes and related costs are expected to more than double in the next quarter century. Therefore, simple and sustainable approaches that can be applied at the public health level are needed to lower diabetes risk.
Dr. Pittas: D2d was designed to test whether 4000 IU per day of vitamin D3 (cholecalciferol) reduces the risk of diabetes among adults at high risk for diabetes, defined in the 2010 ADA guidelines as meeting at least two of three glycemic criteria for prediabetes. A total of 2,423 participants at 22 U.S. study sites were randomized to take a pill containing 4000 IU of vitamin D3 per day or matching placebo and followed for new-onset diabetes for a median of 2.5 years. The study was designed as an event-driven trial with a target total number of diabetes events of 508.
To maximize the study’s ability to observe a treatment effect, participants were asked to refrain from using diabetes-specific and/or weight loss medications during the study and to limit the use of outside-of-study vitamin D to 1000 IU per day from all supplements, including multivitamins.
Dr. Pittas: Approximately one in three U.S. adults age 20 years and older have prediabetes, which is a risk factor for progression to diabetes. Therefore, there’s a continued need for identification of interventions to lower progression to diabetes in populations at high risk. D2d has extensive public health implications, given that the cost of supplementation with vitamin D is low compared to treating diabetes and its complications.
If D2d supports the underlying hypothesis of a link between low vitamin D levels and risk of type 2 diabetes, then vitamin D supplementation would be integrated into conventional medical approaches to prevent type 2 diabetes and ameliorate personal and societal disease burden. Moving forward, our group plans to use study data to answer ancillary questions of importance, e.g., effect of vitamin D supplementation on cardiac risk factors, kidney disease and cancer, and bone health among people at risk for diabetes.