Diabetes is a disease in which the body does not produce or properly use insulin. Insulin is a hormone that is needed to convert sugar, starches and other food into energy. The cause of diabetes continues to be a mystery, although both genetics and environmental factors (such as obesity and lack of exercise) appear to play roles. In the United States, 20.8 million people (7 percent of the population) have diabetes. About 14.6 million have been diagnosed, but 6.2 million people (nearly one-third) are unaware that they have the disease, according to the American Diabetes Association. Credits:  CBS News, American Diabetes Association