Vitamin D has become the cure-all of the vitamin world in recent years. Diseases like osteoporosis, asthma, dementia, hypertension, heart disease, and some cancers have all been linked to a deficiency of the vitamin.

Now vitamin D — a lack of it — appears to be a key player in who goes on to develop type 2 diabetes.

People who have adequate levels of vitamin D are less likely to have type 2 diabetes, even if they are overweight or obese. Since excess weight is generally believed to be the root cause of type 2 diabetes, this appears to be an interesting twist in the already suspected link between vitamin D, obesity, and diabetes.

Worldwide, over a billion people don’t get adequate sun exposure to produce sufficient vitamin D.

Studies have shown that low vitamin D levels and obesity go hand-in-hand. Low levels of vitamin D also increase the likelihood of type 2 diabetes, prediabetes, and metabolic syndrome.

This most recent study compared vitamin D biomarkers among the study participants who ranged from normal weight to morbidly obese; participants were also classified as to whether or not they had any type of glycemic disorder. Researchers measured everyone's vitamin D blood level, as well as vitamin D receptor gene expression in their adipose tissue.

Obese people who did not have diabetes or any other type of glucose metabolism disorder had higher levels of vitamin D. Lower levels of the vitamin were found in lean people who had diabetes or some other form of glucose metabolism disorder. Vitamin D levels among the study participants appeared to be correlated with glucose levels and not their body mass index or weight.

Getting enough vitamin D can be tricky. It is not found naturally in many foods — fatty fish and eggs are two of the few natural sources. Foods like milk and breakfast cereals are often fortified with it.

Outside of food sources (and supplements), the only other source of vitamin D for the human body is sunshine. Vitamin D is made by the body through a series of chemical reactions that occur when the ultraviolet rays of the sun touch the skin.

With a single needle prick, you can have your vitamin D level tested, and your doctor can tell you if you need to take a supplement.

People who live around 33 to 35 degrees north latitude or greater (anywhere north of Los Angeles and Atlanta in the United States) have a difficult time producing enough vitamin D in the winter because the sun never gets high enough in the sky for the ultraviolet rays to penetrate the atmosphere. Worldwide, over a billion people don’t get adequate sun exposure to produce sufficient vitamin D.

According to one of the study’s authors, Manual Macias-Gonzalez, PhD, “The study suggests that vitamin D deficiency and obesity interact synergistically to heighten the risk of diabetes and other metabolic disorders. The average person may be able to reduce their risk by maintaining a healthy diet and getting enough outdoor activity.”

Since vitamin D is a fat soluble vitamin, it is stored in the body. Stocking up on sunshine in the summer months may help get you through the winter months, but don’t count on it.

With a single needle prick, you can have your vitamin D level tested, and your doctor can tell you if you need to take a supplement. Because too much vitamin D can lead to another whole set of health problems, take supplements only when recommended by your doctor.

The study was published in the Journal of Clinical Endocrinology & Metabolism.