What is type 2 diabetes?

Matthew J. Freeby, MD
Endocrinology Diabetes & Metabolism
Type 2 diabetes mellitus is a disease that occurs when blood glucose levels rise. It is usually, but not always diagnosed in adulthood. Risk factors include high risk ethnicity, obesity and family history. There are multiple factors leading to progression, but insulin resistance and a reduction in insulin production are the two biggest reasons for type 2 diabetes development. Under normal circumstances, insulin regulates glucose control in the muscle, liver and adipose tissue. Insulin allows for organs such as the muscle to take in glucose and use it for energy. In those at risk for type 2 diabetes, the body is usually resistant to insulin. This means the body requires more than the normal amount of insulin to do its normal functions. This in turn leads to increased insulin production by the beta cells in the pancreas. For people who ultimately have type 2 diabetes, the pancreas has lost its ability to compensate for an increase in insulin needs. Although the body is producing insulin, there isn’t enough to keep blood sugar in a normal range.
Type 2 diabetes, which is more common than type 1 diabetes, usually occurs in people over 40 and is called adult onset diabetes mellitus. It is also called non insulin-dependent diabetes mellitus. In type 2, your pancreas makes insulin, but your body does not use it properly. The high blood sugar level often can be controlled by following a diet and/or taking medication, although some people must take insulin. Type 2 diabetes is particularly prevalent among blacks, American Indians, Latin Americans and Asian Americans.
Type 2 diabetes develops as a result of the body incorrectly making or using insulin. In people with type 2, the liver, muscle and fat cells become "resistant" to insulin, meaning that these cells need increasing amounts of insulin to respond to the insulin's signal to take up glucose from the bloodstream. To compensate, the pancreas begins producing more and more insulin every time food is consumed. However, the insulin-producing pancreatic cells or beta cells - in people with type 2 diabetes are not able to produce enough insulin, both because of the high demands of the liver, muscle and fat cells and because of beta cell death. About 90% of people with type 2 have some degree of beta cell death at the time of diagnosis. Beta cell function continues to decline over time, leading to progression of the disease and its symptoms. When the pancreas is no longer able to produce enough insulin, glucose is not taken up out of the bloodstream to be metabolized into energy. This causes blood sugar levels to rise.
Scripps Health
Administration
Between 90 and 95 percent of Americans with diabetes have type 2. It develops over time as a result of lifestyle factors, such as obesity and lack of exercise.
RealAge
Administration
Also known as adult-onset or noninsulin-dependent diabetes, this life-long disease is preceded by insulin resistance, a condition where the body does not respond correctly to insulin. Environmental factors such as obesity, low physical activity, and a diet high in sugar and fat can aggravate the body’s resistance to the action of insulin.

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Vinisha J. Patel, MD
Internal Medicine

Type 2 diabetes is a condition where your body's cells stop responding to the effects of insulin and/or when the pancreas stops producing enough insulin. 

Risk factors for type 2 diabetes include obesity, family history, hispanic/african/asian ethnicity, history of gestational diabetes, physical inactivity, poor dietary habits, pre diabetes, and age. 

Type 2 diabetes is diagnosed by the following criteria: a blood glucose taken at any time that is greater than 200, a fasting blood glucose greater than 126, or a hemoglobin A1c greater than 6.5

The hemoglobin A1c level is a measure of how much sugar has stuck to the circulating red blood cells which typically live for about 90 days. The HgbA1c value reflects the average blood sugar for the past 3 months and is normally below 5.6. A level between 5.7 and 6.4 qualifies as "pre diabetes", and as stated above, is a risk factor for developing type 2 diabetes. 

American Red Cross
Administration
With type 2 diabetes, the body makes insulin but not enough to meet the body’s needs, or the body becomes resistant to the insulin produced. Type 2 diabetes is more common among African Americans, Latinos, Asians, certain Native Americans, and Pacific Islanders. 
Jacob Teitelbaum
Integrative Medicine
In type 2 diabetes, your body gets overwhelmed by the demands of processing excess sugar. Eating sugar can also make you overweight, a key risk factor for type 2 diabetes. When you are a type 2 diabetic, you manufacture plenty of insulin, but it just doesn’t work. This is what’s known as “insulin resistance.” Unfortunately, a high insulin level makes you continue to pack on pounds of body fat, which then worsens the insulin resistance.
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In people with type 2 diabetes, insulin is produced, but the cells do not respond to insulin as they should. Glucose has a hard time getting out of the blood and into cells. For some people with type 2 diabetes, diet, exercise, and oral diabetes medication together can help them keep their blood glucose levels on target without insulin injections. But for many people with type 2 diabetes, diet, exercise, and oral diabetes medication are not enough and insulin is needed.

Type 2 diabetes usually occurs in people over the age of 40, but may develop in younger people, especially among certain ethnic groups. Almost all people who develop type 2 diabetes are insulin resistant, and most have a problem with insulin secretion. Some simply cannot produce enough insulin to meet their bodies’ needs, and others have a combination of these problems. Many people with type 2 diabetes initially manage the disease through diet and exercise but, as the ability of the pancreas to secrete insulin decreases, progress to oral medications and/or insulin.

Robert S. Kaufmann, MD
Internal Medicine
Diabetes is a lifelong disease marked by high levels of glucose (blood sugar) in the blood. There are two types of diabetes. With type 1, or insulin-dependent diabetes, the body does not produce insulin on its own. In type 2, the body becomes resistant to insulin.Insulin is a hormone that is essential to the body for regulating glucose levels and metabolism.

Type 2 diabetes is the most common form of diabetes. It can often go undiagnosed for years because the symptoms can be mild and come and go.

Some of the symptoms include: General weakness More frequent urination Blurred vision Fatigue Numbness or tingling of the extremities Dry mouth Some people with type 2 diabetes can manage it by diet and exercising regularly. Others may require oral medicines or insulin injections.
Johns Hopkins Medicine
Administration
Type 2 diabetes, also known as adult-onset diabetes, insulin production by the pancreas is normal or only slightly reduced, but cells are unable to respond efficiently to insulin—a condition referred to as insulin resistance. The onset of type 2 diabetes is usually gradual and tends to affect people over the age of 40, particularly those who are overweight.
In type 2 diabetes, high blood glucose levels (hyperglycemia) lead to excretion of glucose in the urine and an accompanying increase in urine production. People with type 2 diabetes are susceptible to another life-threatening condition known as a hyperosmolar nonketotic state, characterized by extremely high blood sugar levels. This condition usually occurs in elderly persons with some other serious underlying illness. An episode of either diabetic ketoacidosis (DKA) or the hyperosmolar state may be the first indication that someone has type 2 diabetes.
People with diabetes may also suffer from low blood sugar (hypoglycemia) if too much insulin or oral hypoglycemic agent is given for treatment.
After 10 to 20 years of diabetes, patients are likely to develop complications, such as vision disorders, kidney damage, and peripheral nerve degeneration (neuropathy). Strict control of blood glucose can delay or prevent these complications. Loss of sensation in the feet may allow injuries to go unchecked and become infected. In addition, people with diabetes are at increased risk for developing narrowing of the coronary arteries as well as narrowing of arteries supplying the brain and legs. The combination of foot infections and decreased blood supply can lead to gangrene (tissue death), which may require amputation. Diabetes mellitus (and its complications) is the fourth leading cause of death in the United States.
Type 2 diabetes may be controlled with a combination of diet, exercise, and weight loss, although medications (including insulin) are often necessary. Treatment is largely a process of self-management. And although there is no cure, almost all people with diabetes are able to control their symptoms and lead full, productive lives.
Tonya Bolden
Alternative & Complementary Medicine

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. . . .

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.

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Diabetes mellitus is a disease in which the body can't use sugar (glucose) properly. Ninety-five percent of people who have diabetes have type 2 diabetes. Type 2 diabetes occurs when the body doesn't produce enough of the hormone insulin or becomes resistant to its effects. Insulin helps the body use and store glucose, keeping blood sugar at normal level.

While type 2 diabetes is treatable, it increases your risk for heart attack, stroke, and complications related to poor circulation. Diabetes can damage the kidneys, leading to their failure to filter out waste products. Diabetes can also cause eye problems and lead to blindness.

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Healthy Humans
Administration
The number of people diagnosed with diabetes or at risk of developing diabetes is at an all-time high, and it's estimated that nearly one half of all children born in the United States today will get diabetes sometime in their lives.

Type 2 diabetes is the most prevalent form, affecting approximately 17 million individuals. Luckily, most of the risk factors for getting diabetes or complications from diabetes are understood and can be mitigated. The cause of diabetes is related to the improper functioning and activity of the hormone insulin. It is the job of insulin to signal cells to allow glucose to enter. If insufficient amounts of insulin are secreted by the pancreas or if the body's cells become resistant to insulin's signaling, the body is not able to properly utilize glucose. It becomes concentrated in the bloodstream, a condition known as hyperglycemia (high blood sugar).

Type 2 diabetes is primarily an illness of diet and lifestyle. People who are overweight, don't exercise, eat a diet low in fruits and vegetables and high in red meat and saturated fat alter their physiology in a way that increases their risk for developing diabetes. That's why an integrative medicine approach (or a Whole Health approach that combines diagnostic testing for measurement, prescription medicines when necessary, nutritional supplements, and, most importantly, diet, nutrition, and exercise) works well for diabetes management.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.