Type 2 diabetes is a lifelong disease that affects the way your body uses food for energy. The disease develops when the cells of the body become resistant to insulin or when the pancreas cannot make enough insulin. Insulin is a hormone that helps your body's cells get needed energy from sugar. When insulin is not able to do its job, too much sugar builds up in your blood. Over time, this extra sugar in your blood can lead to problems with your eyes, heart, blood vessels, nerves, and kidneys.

Type 2 diabetes usually develops in adulthood; however, more and more children are being diagnosed with type 2 diabetes. Often people who have type 2 diabetes are overweight and get little or no physical exercise.

Sometimes type 2 diabetes develops so slowly that you do not have symptoms until you already have some more serious problems from the disease. Many people have prediabetes-when blood sugar levels are above normal but not high enough to have diabetes-for years before they know they develop type 2 diabetes. For more information on prediabetes, see the topic Prediabetes.

Once you know that you have type 2 diabetes, you will work with your doctor and other health professionals to develop the best treatment plan for you. Treatment usually includes eating healthy foods and spreading carbohydrate throughout the day, exercising regularly, checking your blood sugar levels often, and possibly taking medicine. Working closely with your doctor and other health professionals can help you feel better and more in control of your disease. You can help prevent or delay more serious health problems by keeping your blood sugar within a safe range.

As time goes on, your pancreas may make less and less insulin, which can make it harder to control your blood sugar level. It is important to treat your high blood sugar early anytime your blood sugar level rises above what is safe for you. Treating high blood sugar early can help prevent:

• A hyperosmolar state, which is a life-threatening event that can happen when the blood sugar level is very high. It can occur when a person with type 2 diabetes has an illness, such as a severe case of the flu or other infection; has a heart attack; is not drinking enough liquids and becomes dehydrated; or takes medicines (diuretics) that increase fluid loss or affect mental alertness, especially if liquids are not replaced.
• Long-term diabetes complications, which result from damage to the body's tissues. Persistent high blood sugar can damage the eyes (diabetic retinopathy), kidneys (diabetic nephropathy), nerves (diabetic neuropathy), heart (leading to a heart attack), and blood vessels (leading to strokes, peripheral arterial disease, and possibly amputation).