The message from our doctors is loud and clear: Being overweight is linked to diabetes, a disease in which blood sugar levels range much too high for our own good health. A new study finds this picture is not nearly so simple, but quite a bit more complex. Researchers at Universidad de Málaga in Spain found people with low levels of vitamin D, regardless of whether they are overweight or thin, are more likely to have diabetes.

Vitamin D is known as the "sunshine vitamin" because it is produced by our bodies through simple exposure to sunlight. Vitamin D, despite its name, is actually not a vitamin but a pro-hormone, a substance that amplifies the effects of hormones; it is important to maintaining healthy bones and teeth, while also aiding cell growth and assisting our immune system. Although sunlight is the easiest way to acquire a little necessary D, it can also be absorbed while eating common foods, including eggs, fish, and dairy products. Seemingly, nothing could be easier than getting enough vitamin D; however, up to half of all adults and children worldwide are deficient — more than one billion people around the globe!

How the Sunshine Vitamin Impacts Diabetes Risk

For the current study, a group of researchers investigated the relationships between vitamin D, body mass index (BMI), and diabetes in 118 participants at a hospital associated with University of Málaga and 30 additional participants at a second hospital in Girona, Spain. To start, the team classified all the participants according to BMI and also noted whether they had diabetes, prediabetes, or no glycemic disorders. Next, the researchers made two separate measurements for all the participants: levels of vitamin D in their blood and levels of vitamin D receptor gene expression in their adipose (fat) tissue. Finally, they performed a comparison and analysis.

What did they discover? Obese participants who did not have diabetes, prediabetes, or any sign of a glucose metabolism disorder had higher levels of vitamin D than their diabetic peers. Similarly, thin participants who did have diabetes or a glucose metabolism disorder were more likely to have low levels of vitamin D. The researchers concluded that vitamin D levels are directly correlated with glucose levels, but not with BMI.

“The study suggests that vitamin D deficiency and obesity interact synergistically to heighten the risk of diabetes and other metabolic disorders,” Dr. Manuel Macías-González of University of Málaga and an author of this study said in a press release. One easy step, then, to help you avoid a diabetes diagnosis is getting some sunshine.

Source: Clemente-Potigo M, Munoz-Garach A, Serrano M, et al. Serum 25-Hydroxyvitamin D and Adipose Tissue Vitamin D Receptor Gene Expression: Relationship With Obesity and Type 2 Diabetes. Journal of Clinical Endocrinology & Metabolism. 2015.