Vitamin D and Diabetes

Vitamin D has become very popular over the last decade or so, due in part to several studies that suggest a possible anti-cancer effect. While certainly good for bone health, and deficient in some people, the evidence is still preliminary for other positive effects. This includes diabetes.

In 2010, a study was published by the Endocrine Society that found up to 91% of patients with diabetes were also deficient in vitamin D. However, the researchers stressed they did not know if there was any cause/effect relationship between the two.

There have been a few other studies that have actually found that cause/effect relationship. For example, a 2003 study in the International Journal of Clinical Practice was performed on ten women with diabetes during the winter, when sunlight was lowest, and found that supplementation increased insulin sensitivity by 21%.

However, most of the vitamin D and insulin studies have been observational only; they simply made the observation that in patients with diabetes, vitamin D deficiency was common as well. There may be several reasons for this link, and vitamin D may not play any causal role in treating diabetes.

Evidence from other studies is conflicting.

A study published in Diabetes Care looked at over 5,000 women over the course of seven years; 6% developed diabetes during this period, however, there was no correlation found between diabetes and vitamin D levels.

As a result of these conflicting studies, it is not currently known if vitamin D can help treat diabetes or not. If you are elderly or do not get much sun, it certainly would not hurt to take a daily supplement of D, around 1000 IU per day or so. The recommended daily allowance is 600 for adults, and 800 for the elderly, but up to 4000 IU per day is probably safe to take long term.