Vitamin D Supplementation Reduces the Risk of T2DM 

Large study finds both vitamin D dosage and patient BMI play a role in the effectiveness of supplementation in preventing T2DM. 

Diabetes mellitus has been affecting millions of people worldwide. People with type 2 diabetes are experiencing a shortage of insulin in their bodies; therefore, they can’t maintain normal glucose levels. People with obesity and people that don’t exercise regularly are at higher risk of developing type 2 diabetes mellitus. The goal is to discover supplements that can facilitate in reducing these risk factors. In prior studies, Vitamin D supplementation has been conducted to determine its effectiveness in preventing T2DM. Vitamin D deficiency is another sign associated with T2DM. Most of these trials have been small and have only tested low doses of Vitamin D, and have not been as successful. This study is conducting a meta-analysis of randomized controlled trials (RCTs) with a large group of participants to prove that using Vitamin D supplements can help prevent the risk of T2DM. 

The study used three types of Vitamin D supplements: cholecalciferol, ergocalciferol, and eldecalcitol, in approximately 43,559 participants. All the participants had prediabetes; half of the people were placed in the placebo group, and the rest were placed in the group that received Vitamin D supplements. They conducted nine trials. For the Vitamin D supplementation, they were using lower and higher doses of 1000 IU/day. The trials were conducted for one year. 

The study concluded that the trials with lower Vitamin D supplementation than 1000 IU/day did not show a risk reduction in diabetes and its results were as follows: (RR, 1.02; 95% CI, 0.94–1.10; P = 0.68; I2 = 0%). In contrast, the group that received more than 1000 IU/day Vitamin D supplementation showed a significant improvement in reduction of type 2 diabetes mellitus (1019 cases; RR, 0.88; 95% CI, 0.79–0.99; P = 0.03; I2 = 0%). Another significant finding was that patients with a BMI of less than 30 kg/m^2 had a higher reduction in T2DM with Vitamin D supplementation (95% CI, 0.53–0.89; P = 0.005; I2 = 0%), compared to patients with higher BMI than 30 kg/m^2, (RR, 0.98; 95% CI, 0.83–1.16; P = 0.79; I2 = 0%). Another study had used 4000 IU/day and had recorded a significant reduction in serum FPG and HbA1C, and an improvement in glycemic control.  

The results of this study were successful, as previous studies were unable to provide such significant results. With every study, we will find strengths and weaknesses. Some strengths associated with this study were the large number of participants that they gathered to conduct the study. The larger the group, the better the study will be. Another strength is finding a correlation between Vitamin D supplementation of higher than 1000 IU/day, leading to a reduction of T2DM. A weakness in the study was that the participants were mainly older, which means we are not sure how it would relate to the younger population. Another weakness was that in the study, it was never mentioned which groups had better results comparing the different types of Vitamin D supplements. Since cholecalciferol is more potent, effective, and longer acting than ergocalciferol, we might observe better results in patients with diabetes who take this form of supplementation. But more studies need to be conducted to distinguish if there are any significant differences between these Vitamin D supplements in T2DM. 

Practice Pearls: 

• Vitamin D supplements of higher than 1000 IU/day have shown to be very useful in the reduction of serum FPG and HbA1C and the prevention of T2DM. 
• Vitamin D deficiency is another significant risk associated with type 2 diabetes mellitus. 
• Patients with diabetes with a BMI of lower than 30 kg/m^2 had a higher reduction in T2DM with Vitamin D supplements than patients with a higher BMI of 30 kg/m^2. 

Ahmad Alabdouh, Areeg Bala, Mahmoud Barbarawi, Owais Barbarawi, Yazan Zayed, et al. “Effect of Vitamin D Supplementation on the Incidence of Diabetes Mellitus.” Journal of Clinical Endocrinology & Metabolism, June 4. 2020. Web. August 12, 2020.      https://doi.org/10.1210/clinem/dgaa335 

Charoenngam Nipith and Michael F Holick. “Immunologic Effects of Vitamin D on Human Health and Disease.” Nutrients vol. 12,7 2097. July 15, 2020. Web. August 12, 2020. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7400911/ 

Joan Prifti, PharmD. Candidate, LECOM College of Pharmacy