Vitamin D3 Supplementation Does Not Lower Risk of T2D in Healthy Older Adults

Vitamin D3 supplementation does not significantly reduce the risk of developing type 2 diabetes (T2D) among older adults who are generally healthy and not at high risk, according to research published in the journal Diabetologia.¹ However, authors of the study said that the findings do not exclude the possibility that supplementation among those with vitamin D3 deficiency might be beneficial.

Vitamin D3 Supplementation Does Not Lower Risk of Type 2 Diabetes / kavunchik - stock.adobe.com

Over 38 million people have diabetes in the United States, with between 90% to 95% of cases being T2D.² Although there are certain risk factors for T2D—including having a family history of the disease—most cases can be prevented though lifestyle factors like eating a healthy diet and exercising. Previous research has also found that having a vitamin D3 deficiency is significantly associated with developing type 2 diabetes.³

READ MORE: Type 2 Diabetes Diagnosis at Younger Age Linked with Increased Dementia Risk

“Vitamin D deficiency is common around the world and it has been suggested that this may have unfavourable effects on glucose metabolism and risk of type 2 diabetes,” the authors wrote. “Type 2 diabetes is characterised by dysfunction of pancreatic islet cells and consequent disturbances in insulin synthesis and secretion, and by insulin resistance in the peripheral tissues, resulting in impaired glucose metabolism or overt diabetes. Effects of vitamin D supplementation on glucose metabolism are plausible, because the physiologically active form of vitamin D…is directly involved in the regulation of glucose metabolism by improving islet functioning and reducing insulin resistance.”

Investigators from the University of Eastern Finland and the University of Helsinki conducted a study to investigate the effects of vitamin D3 supplementation on the incidence of T2D in a generally healthy older adult population. The study, called the Finnish Vitamin D Trial (FIND), was a 5 year randomized, placebo-controlled, parallel-arm trial conducted between September 2012 and October 2018.

The study cohort included 2271 male and female patients aged 60 years and older and 65 years and older, respectively. Patients were included if they had no history of cardiovascular disease or cancer. Exclusion criteria included a history of kidney stones, renal failure or dialysis, and use of more than 800 IU per day of vitamin D or 1200 mg per day of calcium. The patients randomly received either 1600 IU or 3200 IU of vitamin D3 per day or placebo. Additionally, a sub cohort of 551 patients took part in more detailed baseline examinations, including blood sampling and follow-up visits at 6, 12 and 24 months.

The study found that there were 31 T2D events in the 1600 IU per day group, 36 in the 3200 IU per day group, and 38 in the placebo group during mean follow up of 4.2 years. After excluding 53 T2D events that occurred in the first 2 follow up years, there was a trend towards increased risk of T2D with increasing vitamin D dose. While there was no difference between the groups after stratifying for age and sex, there was a lower incidence of T2D among those with a BMI of 25 kg/m2 or less. Additionally, 137 more patients were diagnosed with T2D during the mean post-supplementation period of 3.3 years.

“In such populations without a high risk for developing type 2 diabetes, for any intervention to show a benefit in terms of preventing type 2 diabetes development, an impractically large study population would most likely be needed,” the authors concluded. “However, our study results do not exclude the possibility that high-dose vitamin D supplementation could be beneficial among vitamin D-deficient populations with an average risk for type 2 diabetes. Currently, such research data are lacking.”

READ MORE: Diabetes Resource Center

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References

1. Virtanen JK, Hantunen S, Kallio N, et al. The effect of vitamin D3 supplementation on the incidence of type 2 diabetes in healthy older adults not at high risk for diabetes (FIND): a randomised controlled trial. Diabetologia (2024). https://doi.org/10.1007/s00125-024-06336-9

2. Type 2 Diabetes. Report. CDC. May 15, 2024. Accessed December 4, 2024. https://www.cdc.gov/diabetes/about/about-type-2-diabetes.html

3. Abugoukh TM, Al Sharaby A, Elshaikh AO, et al. Does Vitamin D Have a Role in Diabetes? Cureus. 2022 Oct 18;14(10):e30432. doi: 10.7759/cureus.30432. PMID: 36407246; PMCID: PMC9671203.