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Type 2 diabetes is a chronic (lifelong) disease marked by high levels of sugar (glucose) in the blood. Type 2 diabetes is the most common form of diabetes.

See also:

• Diabetes
• Gestational diabetes
• Type 1 diabetes
• Metabolic syndrome

Noninsulin-dependent diabetes; Diabetes - type 2; Adult-onset diabetes

Diabetes is caused by a problem in the way your body makes or uses insulin. Insulin is needed to move blood sugar (glucose) into cells, where it is stored and later used for energy.

When you have type 2 diabetes, the body does not respond correctly to insulin. This is called insulin resistance. Insulin resistance means that fat, liver, and muscle cells do not respond normally to insulin. As a result blood sugar does not get into cells to be stored for energy.

When sugar cannot enter cells, abnormally high levels of sugar build up in the blood. This is called hyperglycemia. High levels of blood sugar often trigger the pancreas to produce more and more insulin, but it not enough to keep up with the body's demand.

People who are overweight are more likely to have insulin resistance, because fat interferes with the body's ability to use insulin.

Type 2 diabetes usually occurs gradually. Most people with the disease are overweight at the time of diagnosis. However, type 2 diabetes can also develop in those who are thin, especially the elderly.

Family history and genetics play a large role in type 2 diabetes. Low activity level, poor diet, and excess body weight (especially around the waist) significantly increase your risk for type 2 diabetes.

Other risk factors include:

• Age greater than 45 years
• HDL cholesterol of less than 35 mg/dL or triglyceride level of greater than 250 mg/dL
• High blood pressure
• History of gestational diabetes
• Previously identified impaired glucose tolerance by your doctor
• Race/ethnicity (African Americans, Hispanic Americans, and Native Americans all have high rates of diabetes)

Often, people with type 2 diabetes have no symptoms at all. If you do have symptoms, they may include:

• Blurred vision
• Erectile dysfunction
• Fatigue
• Frequent or slow-healing infections
• Increased appetite
• Increased thirst
• Increased urination

Type 2 diabetes is diagnosed with the following blood tests:

• Fasting blood glucose level -- diabetes is diagnosed if higher than 126 mg/dL on two occasions.
• Oral glucose tolerance test -- diabetes is diagnosed if glucose level is higher than 200 mg/dL after 2 hours.
• Random (non-fasting) blood glucose level -- diabetes is suspected if higher than 200 mg/dL and accompanied by the classic symptoms of increased thirst, urination, and fatigue (this test must be confirmed with a fasting blood glucose test).

You should see your health care provider every 3 months. At these visits, you can expect your health care provider to::

• Check your blood pressure
• Check the skin and bones on your feet and legs
• Check the sensation on your feet
• Exam the back part of the eye with a special lighted instrument called an ophthalmoscope

The following tests will help you and your doctor monitor your diabetes and prevent complications:

• Have your blood pressure checked at least every year (blood pressure goals should be 130/80 mm/Hg or lower).
• Have your glycosulated hemoglobin (HbA1c) checked every 6 months if your diabetes is well controlled; otherwise every 3 months.
• Have your cholesterol and triglyceride levels checked yearly (aim for LDL levels below 100 mg/dL).
• Get yearly tests to make sure your kidneys are working well (microalbuminuria and serum creatinine).
• Visit your ophthalmologist) at least once a year, or more often if you have signs of diabetic retinopathy.
• See the dentist every 6 months for a thorough dental cleaning and exam. Make sure your dentist and hygienist know that you have diabetes.

For additional information, see diabetes resources.

The risk of long-term complications from diabetes can be reduced. If you control your blood glucose and blood pressure, you can reduce your risk of death, stroke, heart failure, and other complications. Reduction of HbA1c by even 1% can decrease your risk for complications by 25%.

After many years, diabetes can lead to serious problems with your eyes, kidneys, nerves, heart, blood vessels, and other areas in your body.

If you have diabetes, your risk of a heart attack is the same as someone who has already had a heart attack. Both women and men with diabetes are at risk. You may not even have the typical signs of a heart attack.

In general, complications include:

• High blood pressure
• Damage to blood vessels that supply the legs and feet (peripheral vascular disease)
• Stroke
• High cholesterol
• Nerve damage, which causes pain and numbness in the feet, as well as a number of other problems with the stomach and intestines, your heart, and other body organs (See: Diabetic neuropathy)
• Foot sores or ulcers, which can result in amputation
• Worsening of eyesight or even blindness due to
• Diabetic retinopathy (eye disease)
• Macular edema
• Cataracts
• Glaucoma
• Kidney disease and kidney failure (diabetic nephropathy)
• Other complications include:
• Erection problems
• Infections of the skin, female genital tract, and urinary tract

Call 911 immediately if you have:

• Chest pain or pressure
• Shortness of breath
• Fainting or unconsciousness
• Seizure

These symptoms can quickly get worse and become emergency conditions (such as convulsions or hypoglycemic coma).

Call your doctor also if you have:

• Symptoms of high blood sugar (being very thirsty, having blurry vision, having dry skin, feeling weak or tired, needing to urinate a lot)
• Symptoms of low blood sugar (weak or tired, trembling, sweating, feeling irritable, unclear thinking, fast heartbeat, double or blurry vision, unclear thinking feeling, uneasy,)
• Numbness, tingling, pain in your feet or legs
• Sores or infections on your feet
• Problems with your eyesight

Diabetes screening is recommended for:

• Overweight children who have other risk factors for diabetes, starting at age 10 and repeating every 2 years
• Overweight adults (BMI greater than 25) who have other risk factors
• Adults over 45 every 3 years

You can help prevent type 2 diabetes by keeping a healthy body weight and an active lifestyle.

To prevent complications of diabetes, visit your health care provider or diabetes educator at least four times a year. Talk about any problems you are having.

Stay up-to-date with all your vaccinations and get a flu shot every year.

To prevent diabetes-related foot problems, you should:

• Stop smoking if you smoke.
• Improve control of your blood sugar
• Get a foot exam by your health care provider at least twice a year and learn whether you have nerve damage.
• Check and care for your feet EVERY DAY, especially if you already have known nerve or blood vessel damage or current foot problems. Follow the instructions below.
• Make sure you are wearing the right kind of shoes.

American Diabetes Association (ADA). Standards of Medical Care in Diabetes—2009. Diabetes Care. January 2009; 32:S13-S61.

Eisenbarth GS, Polonsky KS, Buse JB. Type 1 Diabetes Mellitus. In: Kronenberg HM, Melmed S, Polonsky KS, Larsen PR. Kronenberg: Williams Textbook of Endocrinology. 11th ed. Philadelphia, Pa: Saunders Elsevier; 2008:chap 31.

U.S.Preventive Services Task Force. Screening for type 2 diabetes mellitus in adults: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med. 2008 Jun 3;148(11):846-54.

In the clinic. Type 2 diabetes. Ann Intern Med. 2007;146:ITC-1-15.

Buchwald H, Estok R, Fahrbach K, Banel D, Jensen MD, Pories WJ, Bantle JP, Sledge I. Weight and type 2 diabetes after bariatric surgery: systematic review and meta-analysis. Am J Med. 2009 Mar;122(3):248-256.e5. Review. PubMed PMID: 19272486.