People who have low levels of vitamin D appear to be more likely to have diabetes, no matter what their body weight is. Vitamin D deficiency has been linked with obesity, Type 2 diabetes, prediabetes, and metabolic syndrome in previous studies.
Researchers at the University of Malaga and the University of Cordoba in Spain looked at two groups of people. One group of 118 people was classified by the body mass index-lean, overweight, obese, or morbidly obese-and whether they were nondiabetic, prediabetic, or diabetic. A second group of 30 people who were obese were also classified as being nondiabetic, prediabetic, or diabetic.
The researchers measured levels of vitamin D in the participants' blood and vitamin D receptor gene expression in their fat tissue. Gene expression is the process by which information from a gene is used in the cells.Vitamin D receptor gene expression in fat tissue has been found to be related to obesity and may be regulated by a metabolite of vitamin D called calcitriol. Vitamin D is made in the skin by exposure to sunlight.
They found that the obese subjects who did not have glucose metabolism problems had higher levels of vitamin D in their blood than did those with diabetes. Lean subjects with diabetes or prediabetes were more likely to have low levels of vitamin D. Vitamin D levels were directly correlated with blood glucose levels, but not with body mass index, and were closely related to glucose metabolism variables.
These findings suggest that vitamin D deficiency is associated more with carbohydrate metabolism than with obesity. "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," said Manuel Macías-González, PhD, of the University of Málaga, one of the study's authors.
The study appeared in the Journal of Clinical Endocrinology and Metabolism.