Reduced childhood vitamin D levels predict diabetes

Friday, December 9, 2011. In an article appearing in the January, 2012 issue of the Journal of Clinical Endocrinology & Metabolism, Micah Olson, MD, of the University of Texas Southwestern Medical Center in Dallas and her associates report that children suffering from obesity and insulin resistance (which are both associated with diabetes) are more likely to have reduced serum levels of vitamin D in comparison with non-overweight children.

The current study evaluated serum 25-hydroxyvitamin D levels, fasting glucose and insulin levels, insulin resistance and other factors in 411 obese and 87 non-overweight children between the ages of six and sixteen residing in North Texas. Dietary information collected from the participants included daily intake of milk, soda, juice, fruit and vegetables, and whether or not the subject regularly ate breakfast.

While 68 percent of non-overweight participants had insufficient vitamin D levels of less than 75 nanomoles per liter (nmol/L) and 22 percent had deficient levels lower than 50, among obese children, the incidence of insufficiency and deficiency rose to 92 and 50 percent. Low vitamin D levels were associated with drinking more sodas and juice as well as with skipping breakfast. Among obese children, a significant relationship was observed between increased insulin resistance with lower vitamin D levels.

In their discussion of the findings, the authors note that "the difference in mean 25-hydroxyvitamin D levels between obese and non-overweight subjects was 18.5 nmol/L. Obese children would need to consume an extra 600 to 1200 IU (the equivalent of six to twelve 8-ounce cups of milk) of cholecalciferol daily to make up the difference in mean 25-hydroxyvitamin D levels seen in our study. Thus, poor dietary habits alone cannot explain the low 25-hydroxyvitamin D levels seen in obese children."

"Our study found that obese children with lower vitamin D levels had higher degrees of insulin resistance," stated Dr Olson, who is affiliated with Southwestern Medical Center's Department of Pediatrics. "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."

"Poor dietary habits such as skipping breakfast and increased soda and juice intake were associated with the lower vitamin D levels seen in obese children," she 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."