Diabetes is a condition of elevated blood sugars in which the body does not make enough insulin and/or the insulin being made cannot be used properly by the body. The body's main fuel is a form of sugar called glucose, which comes from food (after it's been broken down). Glucose enters the blood and is used by cells for energy. To use glucose, the body needs a hormone called insulin, which is made by the pancreas.
Insulin is important because it allows glucose to leave the blood and enter the body's cells. Diabetes develops when your body can't make any or enough insulin, or when it can't properly use the insulin it makes.
There are two main types of diabetes: type 1 and type 2. Type 1 diabetes develops when your body makes little or no insulin. When this happens, glucose can't get into the cells for energy and remains in the blood, causing hyperglycemia (high blood sugar).
Type 1 diabetes is an autoimmune condition. Most people develop type 1 diabetes before the age of 30, but it can also occur in older adults. In North America, 5% to 10% of people with diabetes have type 1 diabetes. It occurs equally among women and men.