Low vitamin D levels may predispose one to type 2 diabetes

By Dr. Ananya Mandal, MDDec 6 2011

A new study shows that people with lower vitamin D levels were more likely to be obese and have higher degrees of insulin resistance, when the hormone becomes less effective at lowering blood sugar.

The team at the University of Texas Southwestern Medical Center in Dallas agreed that their study could not determine if low vitamin D levels played an active role in developing the disease diabetes at all. Dr Micah Olson, lead author of the study, published in the Journal of Clinical Endocrinology and Metabolism, said, “Although our study cannot prove causation, it does suggest that low vitamin D levels may play a role in the development of Type 2 diabetes.”

He added, “Future studies are needed to determine the clinical significance of lower vitamin D levels in obese children, the amount and duration of treatment necessary to replenish vitamin D levels in these children and whether treatment with vitamin D can improve primary clinical endpoints such as insulin resistance.”

This new study examined associations between vitamin D levels and dietary habits in obese children, and tested whether there were correlations between vitamin D levels and markers of abnormal glucose metabolism and blood pressure.

In this study, researchers measured vitamin D levels, blood sugar levels, serum insulin, body mass index (BMI) and blood pressure in 411 obese subjects and 87 control non-overweight subjects. Study participants were also asked to provide dietary information including daily intake of soda, juice and milk, average daily fruit and vegetable intake, and whether or not they routinely skipped breakfast. BMI is a measurement of body fat calculated from weight and height.

The skin helps manufacture vitamin D, but only when exposed to strong sunlight. In the winter and early spring the body's reserves can drop to low levels, particularly if a person has had insufficient exposure in the summer months. Vitamin D can also be derived from certain foods, such as oily fish, eggs and fortified breakfast cereals. Therefore, lack of vitamin D could simply be a sign of a generally unhealthy lifestyle: not getting out for enough exercise in the fresh air, and not eating a good diet explain researchers.

Dr Iain Frame, director of the charity Diabetes UK, said the study “adds to growing evidence of a link between low levels of vitamin D and an increased risk of Type 2 diabetes.” He further said, “However, as the authors note, the exact causes of vitamin D deficiency and its role in the development of Type 2 diabetes are still unclear. Diabetes UK is currently funding research at the University of Glasgow to help establish if people with Type 2 diabetes might benefit from vitamin D supplementation. Until we know more, it is not possible to recommend vitamin D supplements to reduce the risk of Type 2 diabetes and people should not see this as an easy fix. Maintaining a healthy weight by keeping to a healthy diet and undertaking regular physical activity is still the best way to reduce your risk of developing Type 2 diabetes.”