Diabetes is a disease that affects the body's ability to produce or use insulin. There are two main types of diabetes: type 1, where the body does not produce insulin, and type 2, where cells do not respond properly to insulin. Over 25 million Americans have diabetes, with rates increasing with age. Diabetes is diagnosed through blood tests and managed through lifestyle changes like diet and exercise or medical treatment like insulin or other medications. While there is no known way to prevent type 1 diabetes, type 2 diabetes risk can be reduced through maintaining a healthy weight and being physically active.