What if a simple vitamin supplement was enough to reduce the risk of type 2 diabetes? According to a study published on February 7, 2023 in the scientific journal Annals of Internal Medicinepeople with prediabetes can reduce their risk of developing type 2 diabetes by 15% taking a simple food supplement of vitamin D.
Other studies have previously looked at vitamin D supplements in people with prediabetes, but “the observed differences were not statistically significant, and the reported relative risk reductions (10% to 13%) were lower than what each trial had the power to detect (25% to 36%)“, according to the researchers.
Type 2 diabetes: the effects of vitamin D supplements
To reach these conclusions, researchers from Tufts Medical Center, Boston, USA, therefore analyzed three clinical trials that evaluated the effects of vitamin D supplementation on the risk of diabetes. The first participants received vitamin D, while the second group received a placebo and therefore have vitamin D deficiencies.
“In these trials (…), vitamin D reduced the risk of diabetesbut the reported risk reduction was not statistically significant in any trial because the percentages were lower than each trial had the power to detect (…) To increase the statistical power to detect an effect, Drs Kawahara and Jorde (…) and I have combined individual participant data from the three trials in a meta-analysis“, explained Dr. Anastassios G. Pittas, senior author of the study and head of the division of endocrinology, diabetes and metabolism at the Tufts Medical Center.
15% reduction in the transition from prediabetes to type 2 diabetes
Result, following a follow-up of 3 years, researchers found that new-onset diabetes occurred in 22.7% of participants who received vitamin D and in 25% of those who received a placebo. They also discovered that the vitamin D supplementation had also led to a 15% reduction in the transition from prediabetes to type 2 diabetes.
“Ces results indicate a modest benefit of vitamin D in reducing the risk of diabetesin prediabetic adults,” said Dr. Pittas. “However, there are still important unknowns. Specifically, we don’t know the optimal dose or formulation of vitamin D, and we don’t know if we should aim for a specific blood level of vitamin D to maximize benefits in this population, with low or no risk of side effects. Further research will need to be conducted to answer these important questions.”
Vitamin D: what dose to avoid side effects?
Previous studies have shown significant adverse effects for too high a vitamin D intake. Thus physicians must be extremely attentive to the required intake of vitamin D and the safe limits.
Extrapolating these results to the more than 374 million adults worldwide who have prediabetes suggests, however, that inexpensive vitamin D supplementation might delay the development of diabetes in more than 10 million people. As a reminder, in France, “more than 3.5 million people are treated with medication for diabetesor 5.3% of the population” according to Public Health France.
