Many of the 23 million Americans with diabetes have low vitamin D levels. Evidence suggests that vitamin D plays an integral role in insulin sensitivity and secretion. Vitamin D deficiency results in part from poor nutrition, which is one of the most challenging issues for people with diabetes. Another culprit is reduced exposure to sunlight, which is common during cold weather months when days are shorter and more time is spent indoors.

Diet alone may not be sufficient to manage vitamin D levels. A combination of adequate dietary intake of vitamin D, exposure to sunlight, and treatment with vitamin D2 or D3 supplements can decrease the risk of diabetes and related health concerns. The preferred range in the body is 30 - 60 ng/mL of 25(OH) vitamin D.