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Type 2 Diabetes

Reviewed by: HU Medical Review Board | Last reviewed: October 2020.

Type 2 diabetes is a condition that is caused by high blood glucose (sugar). Blood glucose comes from the foods you eat, and it is your main source of energy. Your body makes insulin, a hormone created in the pancreas, to help move glucose from the food you eat into your cells so it can be used for energy. However, in people with type 2 diabetes, the body does not use insulin well. This causes your blood glucose levels to rise, which can lead to serious health complications.1

Type 2 diabetes is the most common form of diabetes, accounting for 90 to 95 percent of all cases of diabetes. The American Diabetes Association (ADA) estimates that 26.8 million adults in the United States have been diagnosed with diabetes. However, the ADA estimates another 7.3 million Americans have diabetes but have not been diagnosed.2-4

What causes type 2 diabetes?

Type 2 diabetes develops when the body does not make enough insulin. This usually begins with insulin resistance, which means the cells in your body do not use insulin well. As your body becomes more insulin resistant, your pancreas tries to make more insulin to keep up. Over time, pancreas cannot make enough insulin and may stop making it altogether. Since there is not enough insulin to move glucose into your cells, it stays in your blood, causing health problems.1

Doctors are not exactly sure why this process happens in some people, but research shows that there are genetic and lifestyle factors that increase a person’s risk of developing the disease. Some of these factors cannot be changed, like age or ethnicity. However, lifestyle factors like diet, exercise, and high blood pressure play a large role in the development of type 2 diabetes.5

How is type 2 diabetes different from type 1 diabetes?

Both type 1 and type 2 diabetes are identified by high blood glucose levels. However, there are important differences between the 2 conditions:6,7


  • In type 1 diabetes, the body is no longer able to make insulin.
  • In type 2 diabetes, the body still makes insulin, but it does not make enough of it or does not use it well. Eventually, it stops making insulin altogether.

Age at diagnosis

  • Type 1 diabetes is often diagnosed in childhood or adolescence, but it can develop at any age.
  • Type 2 diabetes is usually diagnosed in people over 45, but it is seen in people of all ages. It is also increasingly common in children.

Risk factors

  • Family history, along with viral and other environmental factors, are risks factor for type 1 diabetes.
  • Family history, being overweight and/or inactive, and high blood pressures are risk factors for type 2 diabetes.


  • There are no know prevention methods for type 1 diabetes.
  • A healthy lifestyle and weight can prevent type 2 diabetes.


  • People with type 1 diabetes require insulin every day to stay alive.
  • Some people with type 2 diabetes can control their blood glucose levels with exercise and diet changes. Others are treated with medicine or insulin.

What are the symptoms of type 2 diabetes?

Many people who have type 2 diabetes experience no symptoms or their symptoms may be mild. Since the signs and symptoms can come on slowly, people may have type 2 diabetes for years before they are diagnosed with the condition.2

Even though type 2 diabetes can develop without symptoms, there are some common signs of high blood glucose. They can provide clues that you may have diabetes:1,2,8

  • Blurred vision
  • Frequent infections
  • Numbness, tingling, or pain, especially in the legs, feet, arms, and hands
  • Sores or cuts that heal slowly or do not heal
  • Excessive thirst and increased urination
  • Sudden, unexplained weight loss
  • Fatigue
  • Constant hunger

How is type 2 diabetes diagnosed?

There are a few different tests that can be used to diagnose type 2 diabetes by measuring your blood glucose levels. Doctors typically use 1 or more tests when determining if you have diabetes. They include:9

  • Fasting blood glucose test – a blood glucose level of 126 mg/dl or higher is considered diabetes
  • Hemoglobin A1C test – a level of 6.5 percent or higher is considered diabetes
  • Oral glucose tolerance test – this test is mostly used to diagnose gestational diabetes; doctors measure the results of this test differently depending on whether you are being tested for type 2 diabetes or gestational diabetes
  • Random blood glucose test – a blood glucose level of 200 mg/dL or higher is considered diabetes

Testing is simple and usually done in a doctor’s office or a lab. If your test results show that your blood glucose level is high, your doctor may have you take another test on a different day to recheck your level and confirm your diagnosis.9

How is type 2 diabetes treated?

There is no cure for type 2 diabetes, but there are many steps you can take to help control the condition. Your doctor and healthcare team can help you create a treatment plan to help keep your blood glucose levels within a healthy range and prevent complications. Most treatment plans include:1,2

  • Maintaining a healthy weight
  • Eating a healthy diet
  • Getting regular physical activity
  • Taking diabetes medicines and/or insulin as prescribed by your doctor
  • Monitoring your blood glucose at home

Some people are able to manage their type 2 diabetes with diet and exercise alone. However, many also need to take diabetes medicines and/or insulin therapy. Your need for medicine or insulin may change over time.

Can type 2 diabetes be prevented?

Before type 2 diabetes develops, most people have prediabetes. This means your blood glucose levels are higher than normal but not yet high enough to be diagnosed with diabetes. Prediabetes is very common – about 1 out of every 3 adults in the United States has it. About 90 percent of people with prediabetes do not even know they have it. However, if you have prediabetes, your risk of developing type 2 diabetes within 5 to 10 years is dramatically increased.10,11

However, type 2 diabetes can be delayed or even prevented by making some lifestyle changes. Losing weight and regular physical activity are the 2 most important things you can do to manage or prevent prediabetes and, in turn, type 2 diabetes. Both of these things help your body better respond to insulin.10

Even small steps can greatly reduce your risk of developing type 2 diabetes. Regular physical activity means getting at least 30 minutes of brisk walking or a similar activity 5 days a week. Research shows that losing a modest amount of weight – 5 to 7 percent of your starting weight – is helpful. For example, if your starting weight is 200 pounds, that is 10 to 14 pounds.10,11

If you smoke, you should also quit. The risk of developing type 2 diabetes is 30 to 40 percent higher for smokers than nonsmokers.11

To get started with these changes, ask your doctor if there is a National Diabetes Prevention Program (NDPP) offered in your community. The program can help you lower your risk of developing type 2 diabetes by up to 58 percent, or 71 percent if you are over age 60. You can also search online to find an NDPP location near you.

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