What Is Type 2 Diabetes?
Definition | Symptoms | Who's At Risk

Definition Diabetes is a disease that causes an abnormally high level of sugar, or glucose, to build up in the blood. In type 2 diabetes -- previously called noninsulin dependent or adult-onset diabetes -- glucose levels rise because the body is resistant to the effects of insulin and the amount insulin produced by the body is insufficient to overcome this resistance.

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Symptoms
The glucose level in a person with untreated type 2 diabetes may be abnormal for years without causing any symptoms. Type 2 diabetes is then only diagnosed when complications of the disease develop -- such as heart or nerve problems. If early symptoms do occur from high glucose levels, they usually consist of increased thirst and appetite, frequent urination, weight loss, and blurry vision.

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Who's At Risk?
Type 2 diabetes accounts for about 90% of all diagnosed cases of diabetes. Diabetes is common and there are 20 million Americans diagnosed with the disease. But the reality is that there are many more cases of diabetes that are not diagnosed. Experts estimate that 5 million more Americans have type 2 diabetes but haven't been diagnosed yet.

Type 2 diabetes is usually diagnosed in adults over age 40 but can develop in younger people and children. People with a family history of type 2 diabetes have a greater risk of developing the disease. Most people with type 2 diabetes are overweight and physically inactive.

Other risk factors include: history of gestational diabetes (diabetes during pregnancy), polycystic ovary syndrome, high blood pressure, high cholesterol levels, and history of impaired glucose tolerance or impaired fasting glucose. People with metabolic syndrome (a combination of high cholesterol, high blood pressure, abdominal obesity, and abnormal ability to process glucose) are also at higher risk for the disease.

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Next: Anatomy/Function

Anatomy/Function
Insulin Production in the Pancreas | Insulin Function in the Body

Insulin Production in the Pancreas Insulin is a hormone that is produced by specialized cells (beta cells) in the pancreas, located in the abdomen just behind the stomach. The hormone is then released into the bloodstream where it is carried to all the cells in the body.

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Insulin Function in the Body Insulin is required for the entry of glucose into body cells. Once released into the bloodstream, insulin attaches to the cells, triggering a process that allows the glucose to enter them and be converted to energy. Insulin also plays a role in the metabolism of proteins and fats and the storage of glucose in the muscles, liver, and fat tissue.

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Next: Cause

Cause of Type 2 Diabetes

Insulin Resistance Although the pancreas does produce insulin in people with type 2 diabetes, the cells of the body "resist" the insulin's effects. As a result, the glucose circulating in the bloodstream cannot enter the cells and be used for energy.

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Next: Complications

Complications
Damage to Circulatory and Nervous Systems | Damage to Specific Organs

Damage to Circulatory and Nervous Systems People with diabetes, whether type 1 or type 2, have an increased risk of severe complications if the disease goes undiagnosed and untreated -- or if it is poorly managed. High blood glucose levels make it easier for blockages to form in the blood vessels that supply the heart, brain, and legs as well as the rest of the body. High blood glucose can also damage nerves, causing numbness and tingling -- especially in the legs and feet.

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Damage to Specific Organs Diabetes-related damage to a person's circulatory and nervous systems increases the risk of heart attacks, strokes, blindness, kidney failure, and foot and leg amputations. These complications may be present at the time of diagnosis of type 2 diabetes. The good news is that early diagnosis and aggressive treatment of diabetes reduce the risks of developing these complications.

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Next: Treatment

Treatment
Weight Loss, Diet, and Exercise | Medications for Type 2 Diabetes | Sulfonylureas | Metformin | Precose and Glyset | "Glitazones" | Insulin Injections | Glucose Monitoring at Home | Laboratory Tests | Byetta and Januvia | Symlin | Research Continues

Weight Loss, Diet, and Exercise
The first steps in the treatment of type 2 diabetes are weight loss, if needed, and an appropriate diet. Weight loss can reduce the need for medication as well as the risk of developing complications. Weight loss can also reduce the risk of developing type 2 diabetes altogether. Planning a diet that will provide healthy amounts of carbohydrates, protein, fats, and cholesterol and help control body weight often requires close attention from a doctor and possibly a nutritionist. A doctor can also suggest an appropriate exercise regimen.

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Medications for Type 2 Diabetes
If medications are needed, there are several different types of drugs for type 2 diabetes that can be taken by mouth. In addition insulin, taken by injection, may be required in some individuals. Some patients will require a combination of treatments to achieve and maintain good diabetes control.

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Sulfonylureas Drugs in the oldest class of type 2 diabetes medications, called sulfonylureas, increase the amount of insulin produced by the pancreas, thus helping to compensate for the body's resistance to insulin. Patients taking sulfonylureas should not miss meals or take excessive doses: This can cause blood glucose to drop to unsafe levels that, if prolonged, can lead to mental confusion and even coma.

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Metformin A drug from another class of medications, metformin, works three ways: It lowers the amount of glucose produced in the liver, increases the uptake of glucose by the muscles, and decreases the body's resistance to insulin. The side effects of this medication are mainly gastrointestinal, such as diarrhea, nausea, and vomiting. The drug also increases risk of heart failure and increases the production of acid. Therefore the drug should not be taken in elderly people or those with impaired kidney function.

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Precose and Glyset These drugs block enzymes that help digest starches and also slow down the absorption of glucose from the gut. The most common side effects are gastrointestinal: abdominal pain, diarrhea, and gas.

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"TZDs" Another class of medications has a long formal name -- thiazolidinediones -- but is called TZD for short. These drugs work by lowering the entire body's resistance to insulin and may be taken with metformin and/or a sulfonylurea. A patient taking these medications must have regular blood tests to monitor for potential liver problems. Another potential side effect is heart failure.

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Starlix and Prandin
The final class of oral pills is called Meglitinides. Starlix and Prandin are the two available examples. These drugs increase insulin secretion and are taken before meals. They can cause low blood glucose levels and should not be taken if a meal is skipped.

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Insulin Injections
Insulin injections may be needed to manage type 2 diabetes. A newly diagnosed patient with extremely high blood glucose levels may be started on insulin therapy, with a possible switch to pill therapy once the blood glucose has stabilized.

Or, if pill therapy doesn't work to control a patient's blood glucose, insulin can be used instead -- or insulin and pills may be used together.

Insulin is used in pregnant patients with diabetes, in critically ill patients and in patients with diabetes and kidney or liver problems.

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Byetta and Symlin
The newest medications to be introduced for the treatment of type 2 diabetes are Byetta and Symlin. These drugs cannot be taken by mouth and are injected like insulin. They work to slow down stomach emptying and affect glucagon secretion, another hormone involved in determining blood glucose levels.

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Glucose Monitoring at Home
Effective control of diabetes depends on patients' regularly checking (monitoring) their blood glucose levels at home. This usually involves pricking a finger with a small needle, putting a drop of blood on a test strip, and inserting the strip into a machine (blood glucose monitor) that gives the glucose level within a few minutes. Regular monitoring of blood glucose levels helps patients with diabetes keep a record of how well their blood glucose is controlled.

Another option is the GlucoWatch, a watch-like device that checks the blood glucose level of the fluids just under the skin.

Still another technology, continuous glucose monitoring, can be used to discover trends in glucose levels. It does not provide readings for individual tests and the device is not intended for long-term self-care.

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Laboratory Tests
The doctor will also check the patient's blood and run a lab test known as HbA1C to determine how well the blood glucose has been controlled over the last several months. Checking glucose levels at home along with this blood test helps doctors determine if changes in treatment are needed.

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Byetta and Januvia
Byetta and Januvia are two drugs from a new class of drugs that can be used with oral diabetes medicines. They work by improving insulin secretion. Byetta is a subcutaneous injection; Januvia a pill.

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Symlin
Symlin is a synthetic version of a natural hormone that can regulate food intake amongst other actions. Patients taking Symlin often need reduced doses of insulin.

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Research Continues
Prevention and effective treatment of diabetes are the subjects of ongoing and intensive medical research. As new discoveries are translated into useful therapies, products, and services, WebMD will incorporate these advances into its related programs.

If you or someone you love needs to know more about diabetes, please consult a physician. If you need to find a physician, try our Find a Physician Channel. For more information about diabetes, visit our Diabetes Health Center.

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