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Type 2 diabetes

Alternative names

Noninsulin-dependent diabetes mellitus; Diabetes - Type 2


Type 2 diabetes is a chronic, life-long disease that results when the body's insulin does not work effectively. Insulin is a hormone released by the pancreas in response to increased levels of blood sugar (glucose) in the blood.

See also type 1 diabetes .

Causes, incidence, and risk factors

Diabetes is caused by a problem in the way your body makes or uses insulin. Insulin is necessary for glucose to move from the blood to the inside of the cells.

Unless glucose gets into cells, the body cannot use it for energy. Excess glucose remains in the blood, and is then removed by the kidneys. The symptoms inlcude excessive thirst , frequent urination , hunger , and fatigue .

There are several types of diabetes:

  • Type 1 diabetes, which requires total insulin replacement in order to live because the body does not make adequate amounts
  • Type 2 diabetes, which is related to insulin resistance (lack of the ability of the body to respond to insulin appropriately) and is often accompanied by obesity and high cholesterol
  • Gestational diabetes , which occurs during pregnancy

Diabetes affects up to 6% of the population in the U.S. Type 2 diabetes accounts for 90% of all cases.

A main component of type 2 diabetes is "insulin resistance". This means that the insulin produced by your pancreas cannot connect with fat and muscle cells to let glucose inside and produce energy. This causes hyperglycemia (high blood glucose).

To compensate, the pancreas produces more insulin. The cells sense this flood of insulin and become even more resistant, resulting in a vicious cycle of high glucose levels and often high insulin levels.

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

Genetics play a large role in type 2 diabetes and family history is a risk factor. However, 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:

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


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

  • increased thirst
  • increased urination
  • increased appetite
  • fatigue
  • blurred vision
  • frequent and/or slow-healing infections (including bladder, vaginal, skin)
  • erectile dysfunction in men

Signs and tests

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.
  • 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.)
  • Oral glucose tolerance test -- diabetes is diagnosed if glucose level is higher than 200 mg/dL after 2 hours.


The first goals are to eliminate the symptoms and stabilize your blood glucose levels. The ongoing goals are to prevent long-term complications and prolong your life. The primary treatment for type 2 diabetes is exercise and diet.


You should learn basic diabetes management skills. They will help prevent complications and the need for medical care. These skills include:

  • How to test and record your blood glucose (see blood glucose monitoring ).
  • What to eat and when.
  • How to take medications, if indicated.
  • How to recognize and treat low and high blood sugar.
  • How to handle sick days.
  • Where to buy diabetes supplies and how to store them.

It may take several months to learn the basic skills. Once your condition has stabilized, continue to educate yourself about the disease process, how to control and live with diabetes, and long-term complications of the disease. Over time, stay current on new research and treatment.


Blood sugar testing, or self-monitoring of blood glucose, is done by checking the glucose content of a small drop of blood. Regular testing tells you how well diet, exercise, and medication are working together to control diabetes.

The results of the test can be used to adjust meals, activity, or medications to keep blood sugar levels in an appropriate range. Testing provides valuable information for the health care provider and identifies high and low blood sugar levels before serious problems develop.

When testing blood sugars yourself, a glucometer is used. A glucometer is a small device that provides an exact reading of blood glucose. A test strip is used to collect a small drop of blood, obtained by pricking the finger with a small, specially-designed needle (called a lancet).

The strip is then placed in the meter. Results are available within 30 to 45 seconds. A health care provider or diabetes educator will help set up an appropriate testing schedule for you. You will also be taught how to respond to different ranges of glucose values obtained when you self-test.

Tests are usually done before meals and at bedtime. More frequent testing may be indicated during illness or stress. Accurate record keeping of test results will make them more useful for planning how to best control your diabetes.


Meal planning includes choosing healthy foods, eating the right amount of food, and eating meals at the right time. You should work closely with your health care provider to learn how much fat, protein, and carbohydrates you need in your diet. Your specific meal plans need to be tailored to your food habits and preferences. A registered dietitian can be helpful in determining your specific, individual dietary needs.

In type 2 diabetes, weight management and a well-balanced diet are important. Some people with type 2 diabetes can stop medications after intentional weight loss, although the diabetes is still present. Consultation with a registered dietitian is an invaluable planning tool.


Regular exercise is important for everyone, but especially if you have diabetes. Regular exercise helps control the amount of glucose in the blood. It also helps burn excess calories and fat to achieve optimal weight.

Exercise improves overall health by improving blood flow and blood pressure . It naturally decreases insulin resistance even without weight loss. Exercise also increases the body's energy level, lowers tension, and improves your ability to handle stress. Everyone should obtain medical approval before starting an exercise program, but this is especially important if you have diabetes.

The following should be considered:

  • Choose an enjoyable physical activity that is appropriate for the current fitness level.
  • Exercise every day, and at the same time of day, if possible.
  • Monitor blood glucose levels by home testing before and after exercise.
  • Carry food that contains a fast-acting carbohydrate in case blood glucose levels get too low during or after exercise.
  • Wear a diabetes identification bracelet and carry change for a phone call in case of emergency.
  • Drink extra fluids that do not contain sugar before, during and after exercise.
  • Changes in exercise intensity or duration may require modification of your diet or medication to keep blood glucose levels in an appropriate range.


When you cannot achieve normal or near-normal blood glucose levels with diet and exercise, medication is added to the treatment plan. Your doctor will start you on oral (by mouth) medicines, such as:

  • Oral sulfonylureas (like glimepiride, glyburide, and tolazamide) trigger the pancreas to make more insulin.
  • Biguanides (Metformin) tell the liver to decrease its production of glucose, which increases glucose levels in the blood stream.
  • Alpha-glucosidase inhibitors (such as acarbose) decrease the absorption of carbohydrates from the digestive tract, thereby lowering the after-meal glucose levels.
  • Thiazolidinediones (such as rosiglitazone) help insulin work better at the cell site. In essence, they increase the cell's sensitivity (responsiveness) to insulin.
  • Meglitinides (including repaglinide and nateglinide) trigger the pancreas to make more insulin in response to how much glucose is in the blood.

If you continue to have poor blood glucose control despite lifestyle changes and using oral medicines, your doctor will prescribe insulin. Insulin may also be prescribed if you have had a bad reaction to oral medicines. Insulin must be injected under the skin using a syringe and cannot be taken by mouth.

Insulin preparations differ in how fast they start to work and how long they work. The health-care professional will determine the appropriate type of insulin to use and will counsel you on what time of day to use it.

More than one type may be mixed together in an injection to achieve the best control of blood glucose. The injections are needed, in general, from one to four times a day. You will be taught how to give yourself injections by your doctor or a diabetes educator referred by your doctor.


People with diabetes are prone to foot problems because of complications caused by damage to blood vessels and nerves and decreased ability to fight infection. Blood flow to the feet may become compromised and damage to the nerves may cause an injury to the foot to go unnoticed until infection develops. Death of skin and other tissue can occur. If left untreated, amputation of the affected foot may ultimately be necessary.

To prevent injury to the feet, diabetics should adopt a daily routine of checking and caring for the feet as follows:

  • Check your feet every day, and report sores or changes and signs of infection.
  • Wash feet every day with lukewarm water and mild soap, and dry them thoroughly.
  • Soften dry skin with lotion or petroleum jelly.
  • Protect feet with comfortable, well-fitting shoes.
  • Exercise daily to promote good circulation.
  • See a podiatrist for foot problems, or to have corns or calluses removed.
  • Remove shoes and socks during a visit to the health care provider to remind them to examine your feet.
  • Discontinue smoking because it worsens blood flow to the feet.


A person with type 2 diabetes should have a visit with a diabetes care provider every three months. A thorough three-month evaluation includes:

  • Glycosylated hemoglobin ( HbA1c ) is a weighted three-month average of what your blood glucose has been. This test measures how much glucose has been sticking to the red blood cells. It also indicates how much glucose has been sticking to other cells. A high HbA1c is an indicator of risk for long-term complications. Currently, the ADA recommends an HbA1c of less than 7% to protect oneself from complications. This test should be done every three months.
  • Blood pressure check.
  • Foot and skin examination.
  • Ophthalmoscopy examination.
  • Neurological examination.

The following evaluations should be done at least annually:

  • Random microalbumin (urine test for protein).
  • BUN and serum creatinine.
  • Serum cholesterol, HDL, and triglycerides.
  • ECG .
  • Dilated retinal exam.

Support Groups

For additional information, see diabetes resources .

Expectations (prognosis)

The risks of long-term complications from diabetes can be reduced. Those with the best control of blood glucose and blood pressure significantly reduce their risk of death, stroke, heart failure, and other complications. Reduction of HbA1c by even one percentage point can decrease your risk for complicatons by 25%.


Emergency complications include diabetic coma .

Long-term complications include:

  • diabetic retinopathy (eye disease)
  • diabetic nephropathy (kidney disease)
  • diabetic neuropathy (nerve damage)
  • peripheral vascular disease (damage to blood vessels/circulation)
  • high cholesterol, high blood pressure, atherosclerosis , and coronary artery disease

Calling your health care provider

Call your health care provider immediately if you have:
  • trembling
  • weakness
  • drowsiness
  • headache
  • confusion
  • dizziness
  • double vision
  • lack of coordination

These symptoms can rapidly progress to emergency conditions (such as convulsions , unconsciousness , or hypoglycemic coma ).


Everyone over 45 should have their blood glucose checked at least every three years. Regular testing of random blood glucose should begin at a younger age and be performed more often if you are at particular risk for diabetes.

Maintain a healthy body weight and keep an active lifestyle to help prevent the onset of type 2 diabetes.

Update Date: 10/10/2003

A.D.A.M. editorial. Previous review by Todd T. Brown, M.D., Division of Endocrinology and Metabolism, Johns Hopkins Hospital, Baltimore, MD. Review provided by VeriMed Healthcare Network (5/1/2002).

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Last updated: Tue, 06 Jan 2009 00:20:03 GMT