Effect of Vitamin D Supplementation on Oral Glucose Tolerance Among Obese Adolescents

Childhood obesity is a rapidly growing epidemic in the US and the world. Current estimates suggest that 30% of our nation's children are either overweight ot obese. Obesity is a major risk factor towards the development of insulin resistance, which, in turn is a major risk factor for the development of type 2 diabetes. Prior research has suggested that vitamin D therapy may be a safe, inexpensive, and effective method of reducing insulin resistance and a person's risk of developing diabetes. The investigators' prior studies have shown that daily 4,000 IU vitamin D therapy is a safe and effective method of improving insulin resistance based on a calculation called the HOMA-IR. The next step in identifying whether vitamin D truly improves insulin resistance is to use oral glucose tolerance testing (OGTT), which is a better real-life measure of insulin resistance compared to the previously used HOMA-IR.