What Is Type 2 Diabetes?

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

There are 3 main forms of diabetes: type 1 diabetes, type 2 diabetes, and gestational diabetes. Type 2 diabetes is the most common form, accounting for 90 to 95 percent of all cases of diabetes.1,2

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.1

In people with type 2 diabetes, the body works hard to release enough insulin to keep blood glucose levels down. Eventually, the body cannot make enough insulin to keep up. Since there is not enough insulin to move glucose into your cells, as well as the inability of cells to respond to insulin, it stays in the blood instead. Over time, this extra glucose in your blood causes a variety of health problems.1

Who gets type 2 diabetes?

The American Diabetes Association estimates that 26.8 million adults in the United States have been diagnosed with diabetes. However, another 7.3 million Americans have diabetes but have not been diagnosed. Another 88 million people in the United States have prediabetes, and there are 1.5 million new cases of diabetes each year. Prediabetes is an early sign of the body’s resistance to insulin, and it puts you at high risk for developing type 2 diabetes.3

About 210,000 Americans under the age of 20 are estimated to have diagnosed diabetes, while 14 million ages 65 and older have the condition.3

Diabetes rates in the United States vary by race/ethnicity:3

  • 7.5 percent of white people
  • 9.2 percent of Asian Americans
  • 12.5 percent of Hispanics
  • 11.7 percent of Blacks
  • 14.7 percent of American Indians/Alaskan Natives

What causes type 2 diabetes?

Type 2 diabetes develops when the body does not make enough insulin. Doctors are not exactly sure why some people cannot make enough insulin, but research shows that there are some genetic and environmental factors that increase a person’s risk of developing the disease.1,4

Some of these factors cannot be changed, such as family history, age, or ethnicity. However, lifestyle factors like diet and exercise play a large role in the onset of type 2 diabetes. You are more likely to develop type 2 diabetes if you:5

  • Are overweight (BMI between 25 and 29.9) or obese (BMI of 30 or greater)
  • Are age 45 or older
  • Have a family history of diabetes
  • Are Black, Alaskan Native, American Indian, Asian American, Hispanic/Latino, Native Hawaiian, or Pacific Islander
  • Have high blood pressure
  • Have low HDL levels (good cholesterol) or high triglyceride (a type of fat found in the blood) levels
  • Have a history of gestational diabetes or gave birth to a baby that weighed more than 9 pounds at birth
  • Are not physically active
  • Have a history of heart disease or stroke
  • Have depression
  • Have polycystic ovary syndrome (PCOS)

What are the symptoms of type 2 diabetes?

Many people who have type 2 diabetes have no symptoms, or their symptoms are mild. Since the symptoms and signs can come on slowly, you can have type 2 diabetes before you are diagnosed with the condition.

Even though you may not have symptoms, there are some warning signs of high blood sugar that can provide clues that you may have diabetes. Common symptoms of type 2 diabetes include:1,4,6

  • Blurred vision
  • Frequent infections
  • Numbness or tingling, 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 and tested?

Since most people who develop type 2 diabetes do not experience symptoms, measuring excess blood sugar or blood glucose levels is the main way to diagnose diabetes. In most cases, diabetes will be detected during routine laboratory testing as part of a check-up. If you have already been diagnosed with diabetes, regular blood sugar testing can help you see how well you are controlling your blood sugar levels.

There are 4 tests that are commonly used to diagnose and help people manage their type 2 diabetes:7

  • Fasting blood glucose test
  • Hemoglobin A1C test
  • Oral glucose tolerance test (usually used to test for gestational diabetes in pregnant women)
  • Random blood glucose test

Testing recommendations include:1,8

  • People over age 45 should have an initial test; if results are normal, testing should be done every 3 years
  • Anyone who is overweight or has other risk factors for diabetes, including high blood pressure and a family history of diabetes, should be tested each year
  • Any woman who is pregnant should be tested between 24 and 28 weeks of pregnancy; women who previously had gestational diabetes should be tested every 3 years
  • Anyone who has been diagnosed with prediabetes should be tested each year
  • Anyone who is experiencing any of the common symptoms of high blood sugar should be tested as soon as possible

How is type 2 diabetes treated?

There is no cure for type 2 diabetes. However, there are many steps you can take to help control your type 2 diabetes. Your doctor can help you develop a treatment plan to keep your blood sugar levels within a healthy range and prevent complications. Most treatment plans include:1,4

  • Maintaining a healthy weight
  • Eating a healthy diet
  • Getting regular exercise
  • Taking diabetes medicines and/or insulin as prescribed by your doctor
  • Monitoring your blood sugar 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. Someone’s need for medication or insulin may change over time.

What is the outcome for type 2 diabetes?

Following your treatment plan can help control your symptoms, improve your quality of life, and reduce the risk of long-term diabetes complications. Studies have shown that people who have well-managed type 2 diabetes have the same life expectancy of people without diabetes.9

However, if not managed, type 2 diabetes can cause serious, long-term complications, including:1

  • Eye and vision problems
  • Foot problems
  • Gum disease and other dental issues
  • Heart disease and stroke
  • Kidney disease
  • Nerve damage
  • Sexual and bladder problems

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