The most common form of diabetes is type 2 diabetes. About 90 to 95 percent of people with diabetes have type 2. This form of diabetes is associated with older age, obesity, family history of diabetes, previous history of gestational diabetes, physical inactivity, and ethnicity. About 80 percent of people with type 2 diabetes are overweight.

Type 2 diabetes is increasingly being diagnosed in children and adolescents. However, nationally representative data on prevalence of type 2 diabetes in youth are not available.

When type 2 diabetes is diagnosed, the pancreas is usually producing enough insulin, but for unknown reasons, the body cannot use the insulin effectively, a condition called insulin resistance. After several years, insulin production decreases. The result is the same as for type 1 diabetes--glucose builds up in the blood and the body cannot make efficient use of its main source of fuel.

The symptoms of type 2 diabetes develop gradually. Their onset is not as sudden as in type 1 diabetes. Symptoms may include fatigue or nausea, frequent urination, unusual thirst, weight loss, blurred vision, frequent infections, and slow healing of wounds or sores. Some people have no symptoms.

Alternative names
Noninsulin-dependent diabetes mellitus; Diabetes - Type 2

Definition
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.

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

Symptoms
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.

Treatment
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.