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Preventing Type 2 Diabetes through Vitamin D3 Supplementation

Aug 10, 2019
Editor: David L. Joffe, BSPharm, CDE, FACA

Author: Usif Darwish, PharmD Candidate, Florida A&M University, College of Pharmacy & Pharmaceutical Sciences

Can Vitamin D3 supplementation really help to prevent diabetes?

Vitamin D deficiency has become a topic of debate in many areas of medicine. It has been linked to a myriad of conditions ranging from anxiety and depression, all the way to certain forms of cancer. Vitamin D plays a key role in the physiology of the body’s bone structure and health, and an integral role in the intestinal absorption of calcium. A deficiency of Vitamin D has been linked to a decrease in bone mass and an increase in bone resorption. Over time, the decrease in bone mass and the increase in bone mineral resorption will likely lead to osteoporosis, fractures, and falls. Over the last few decades, providers have noticed a possible risk that linked Vitamin D3 deficiency to the increased risk of developing Type 2 Diabetes Mellitus.


Certain populations are placed at a higher risk for Vitamin D deficiency. These groups include dark-skinned individuals, patients who are institutionalized, patients who have nutrient malabsorption (e.g. IBD patients), and finally, patients with obesity. Although the other high-risk individuals are important, this article focuses on the link between Vitamin D deficiency and type 2 diabetes. Obesity is a major risk factor for developing type 2 diabetes, and it has been shown that more than 90% of patients with type 2 diabetes are overweight or have obesity. This vitamin D deficiency may be attributed to the lifestyle that patients with excess weight live. These patients may not be attaining the proper amounts of vitamins and nutrients that our body requires to remain healthy. Diet and exercise are major factors in Vitamin D deficiency, which are two factors that patients with obesity often struggle with as well. People who often stay indoors for extended periods and patients who do not eat Vitamin D rich foods are at risk for becoming deficient in Vitamin D. This can be traced back to patients with type 2 or obesity because their typical diet is not rich in vitamins and some patients live a sedentary lifestyle.

In this multicenter, randomized, placebo-controlled trial, researchers set out to explore the relationship between low Vitamin D levels and the risk of developing type 2 diabetes because there are observational studies that support the link between the two, but there are no studies that explore whether the supplementing of Vitamin D reduces the risk of diabetes in patients. They randomly assigned adults who met at least 2 of the 3 diagnostic criteria for prediabetes (FPG level of 100-125 mg/dL; Glucose Tolerance Test of 140 to 199 mg/dL; and an A1C of 5.7 to 6.4%) to two groups. The first group was comprised of patients who were to receive 4000 IU of Vitamin D3 every day, while the second group was comprised of the placebo-controlled group. The primary outcome of the study was to measure the time-to-event analysis of new-onset diabetes. There were a total of 2423 participants in the trial that underwent randomization. 1211 patients were to receive 4000 IUs of Vitamin D3, while 1212 patients were placed in the placebo group. After a median followup of 2.5 years, it was found that the primary outcome had occurred in 293 patients that were placed in the Vitamin D3 group, while the primary outcome occurred in 323 patients that were placed in the placebo group (9.39 and 10.66 events per 100 person-years, respectively). The hazard ratio for vitamin D as compared with placebo was 0.88 (0.95% confidence interval, 0.75 to 1.04; P=0.12). This statistical analysis shows that there was no significant difference between the two groups.

Through the study, it was shown that patients who received 4000 IUs of Vitamin D3 supplementation daily were at no significant advantage in not developing type 2 diabetes in comparison to their placebo-controlled counterparts. The researchers reference several other trials, which took place in Norway and Japan, that came to the same conclusion: that even if you increase the dose of Vitamin D3 to 20,000 (Norway), or if you change the Vitamin D analogue to that of Eldecalcitol, you will yield the same results that show an insignificant decrease in the development of type 2 diabetes. 

Practice Pearls:

  • Patients who received vitamin D3 supplementation were at the same risk of developing diabetes as compared to the placebo group
  • Even when changing the dose and the type of vitamin D, patients were still just as likely to develop type 2 diabetes.
  • Patient education and motivation of healthy eating and exercise remains an effective way of preventing type 2 diabetes and the potential comorbidities that manifest as a result.


American Society for Metabolic and Bariatric Surgery. (2014, December 30). Type 2 Diabetes and Obesity: Twin Epidemics. Retrieved June 30, 2019, from https://asmbs.org/resources/weight-and-type-2-diabetes-after-bariatric-surgery-fact-sheet

Meer, I. M., Karamali, N. S., Boeke, A. J., Lips, P., Middelkoop, B. J., Verhoeven, I., & Wuister, J. D. (2006). High prevalence of vitamin D deficiency in pregnant non-Western women in The Hague, Netherlands. The American Journal of Clinical Nutrition,84(2), 350-353. doi:10.1093/ajcn/84.2.350

Pittas, A. G., Dawson-Hughes, B., Sheehan, P., Ware, J. H., Knowler, W. C., Aroda, V. R., . . . Staten, M. (2019). Vitamin D Supplementation and Prevention of Type 2 Diabetes. The New England Journal of Medicine. doi:10.1056/nejmoa1900906


Usif Darwish, PharmD Candidate, Florida A&M University, College of Pharmacy & Pharmaceutical Sciences