A new US study suggests that the combination of being obese and having insufficient blood vitamin D concentrations may put people at an even greater risk of insulin resistance – a major risk factor for type 2 diabetes – than either factor alone.
To investigate a potential association between vitamin D levels and the risk of diabetes in obese patients, the observational study analyzed the data on serum vitamin D concentrations and indicators of insulin resistance and diabetes from 5,806 adult participants of the National Health and Nutrition Examination Survey (1). The analysis showed that the participants with obesity who had sufficient levels of vitamin D had insulin resis-tance almost 20 times more often than the overall study population. In obese individuals whose serum vitamin D level was low, insulin resistance was much higher: about 32 times more common than the average population.
The researchers noted that the study was based on data from individuals at a single point in time and was therefore unable to determine whether there was a cause-and-effect relationship among vitamin D, obesity and insulin resistance. Thus, it was not clear whether obesity itself caused a low vitamin D level or if it was the other way around. Further studies would be necessary to indicate whether vitamin D supplements are effective in reducing the risk of insulin resistance and diabetes in obese individuals. This would be an inex-pensive and practical prevention strategy compared to the difficulty involved in healthy weight loss. As vitamin D deficiency may be just one of many already known risk factors associated with insulin resistance and diabetes, comprehensive prevention strategies (including physical activity) would be needed to keep diabetes under control.
Vitamin D is stored in adipose fat tissues, which prevents the body from using it. As a result, people who are overweight are already more likely to have low levels of serum vitamin D. Vitamin D deficiency is thought to be associated with multiple health conditions including diabetes, cardiovascular diseases including stroke, depression, dementia and other conditions.