Vitamin D is a nutrient that is vital for many physiological functions. It is a fat-soluble vitamin that promotes the appropriate absorption of calcium in the body, and thus plays a central role in bone health. It is also involved in many other processes, including neuromuscular and immune system functions and various inflammatory pathways. As such, vitamin D deficiency is relevant in a variety of health conditions, including bone disorders, cancers, and diabetes.

Vitamin D and Type 1 Diabetes

It is known that many different cell types can be affected directly by vitamin D, including the pancreatic beta cells (which secrete insulin), as well as immune cells

Research has shown that lower than adequate levels of vitamin D are associated with an increased risk for developing various autoimmune conditions, including type 1 diabetes. Also, adequate vitamin D levels may help support glucose metabolism by several mechanisms, including direct effects on pancreatic beta cells, as well as by improving insulin sensitivity.

In fact, a recent study conducted on youth with type 1 diabetes revealed that

Patients under vitamin D supplementation exhibited a better metabolic control and a lower insulin requirement than not supplemented children, suggesting a role of vitamin D treatment in glycemic control and insulin sensitivity.

More research is needed to fully elucidate the mechanisms underlying the positive effects on vitamin D in helping to prevent type 1 diabetes, as well as in improving glycemic control. However, achieving optimal vitamin D levels, especially in those predisposed to developing type 1 diabetes, as well as in those with type 1 diabetes appears to be a reasonable strategy for prevention and improved outcomes in these patient populations.

Vitamin D and Type 2 Diabetes

Numerous studies have demonstrated that patients with obesity, metabolic syndrome, and type 2 diabetes are more likely to be deficient in vitamin D as compared to healthy controls. Among those with type 2 diabetes, it is estimated that approximately 20% are deficient in vitamin D.

Also, among patients with type 2 diabetes, lower levels of vitamin D are linked to worse glycemic control as compared to those with normal vitamin D levels. A recent literature review highlights that more investigation into the efficacy of vitamin D supplementation in this population is needed. As of now, the experts suggest that vitamin D supplementation could be effective at improving glycemic control in vitamin D deficient or non-obese type 2 diabetes patients.

Vitamin D Supplementation

Vitamin D deficiency is a widespread and global issue that can usually be prevented. Vitamin D can be found in a few food sources, such as fatty fish, some organ meats, egg yolks, or fortified products (e.g., milk). Alternately, it can be taken orally as a supplement and is also produced in the body in response to sunlight.

Although it is important to get enough vitamin D, too much vitamin D can also be harmful. Experts explain that, Vitamin D toxicity can cause non-specific symptoms such as anorexia, weight loss, polyuria, and heart arrhythmias. More seriously, it can also raise blood levels of calcium which leads to vascular and tissue calcification, with subsequent damage to the heart, blood vessels, and kidneys.

The specific recommended upper limits differ based on age and other factors. Thus, it is important to consult with a healthcare provider about supplementing vitamin D and how to do so safely. They may perform testing for vitamin D deficiency and advise you concerning the specific supplementation recommendations for you, if needed.

Summary

It has been shown that adequate vitamin D levels may help protect against the development of type 1 and type 2 diabetes, although the exact reasons for this are not entirely understood yet. Furthermore, adequate vitamin D intake may help improve glycemic control in patients with diabetes. For patients with diabetes or those at risk for developing the condition, it is reasonable to talk to a healthcare provider about further testing for vitamin D deficiency and discuss the need for the appropriate supplementation.