In a study funded by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) it was found that taking a vitamin D supplement does not prevent type 2 diabetes in adults at high risk. D2d(link is external) is the largest study to directly examine if daily vitamin D supplementation helps keep people at high risk for type 2 diabetes from developing the disease.

The study included adults aged 30 or older and assigned participants randomly to either take 4,000 International Units (IU) of the D3 (cholecalciferol) form of vitamin D or a placebo pill daily. All study participants had their vitamin D levels measured at the start of the study. At that time, about 80% of participants had vitamin D levels considered sufficient by U.S. nutritional standards.

A diverse group of participants with a range of physical characteristics, including sex, age, and body mass index, as well as racial and ethnic diversity were enrolled in the D2d study. This representation helps ensure that the study findings could be widely applicable to people at high risk for developing type 2 diabetes.

“In addition to the study’s size, one of its major strengths is the diversity of its participants, which enabled us to examine the effect of vitamin D across a large variety of people,” said lead author Anastassios G. Pittas, M.D., principal investigator from Tufts Medical Center, Boston.

At the end of the study, 293 out of 1211 participants (24.2%) in the vitamin D group developed diabetes compared to 323 out of 1212 (26.7%) in the placebo group – a difference that did not reach statistical significance. The study was designed to detect a risk reduction of 25% or more.

Dr. Veronica Piziak will be speaking on the topic of Diabetes at the upcoming Focus on Women’s Health Conference, July 15-18 in Kiawah Island, South Carolina. Visit sma.org/womens-health for additional information.