What Causes Type 2 Diabetes

A man and a boy are outside playing basketball.

You can prevent or delay type 2 diabetes with proven, achievable lifestyle changes—such as losing a small amount of weight and being more physically active—even if you’re at high risk.

There’s more to why people get type 2 diabetes than you may know. Although lifestyle is a big part, so are family history, age, and race. Learn about what causes type 2 diabetes and how you can help lower your risk.

You’ve probably heard the expression, “you can’t judge a book by its cover.” In the same way we can’t tell what’s inside a book without reading it, we can’t look at a person and know if they’re at risk of type 2 diabetes.

It’s true that being overweight is a risk factor for developing type 2 diabetes, but your family history, age, and race are risk factors too.

Learn about what causes type 2 diabetes, and how you can help lower your risk.

Diabetes Factors

If you have type 2 diabetes, your body doesn’t use insulin well and can’t keep blood sugar at normal levels. We don’t know exactly why this happens, but we do know factors that may increase a person’s risk of developing type 2 diabetes. You may be at risk if you:

  • Have prediabetes.
  • Are overweight.
  • Are 45 years or older.
  • Have a parent, brother, or sister with type 2 diabetes.
  • Are physically active for less than 150 minutes a week.
  • Have ever had gestational diabetes (diabetes during pregnancy) or given birth to a baby who weighed more than 9 pounds.
  • Are African American, Hispanic/Latino American, American Indian, or Alaska Native (some Pacific Islanders and Asian Americans are also at higher risk).

The Fat You Can’t See

Although a person looks thin on the outside, they may have fat on the inside that nobody can see that puts them at risk of type 2 diabetes. How is this possible?

There are two kinds of fat:

  • Fat that’s stored just under the skin. This is fat that we may be able to feel on the outside, like on our arms and legs.
  • Fat that’s stored in our stomach and surrounds important internal organs. We can’t see this hidden, or “visceral” fat from the outside.

Research shows that visceral fat is an important factor in how our hormones work. It’s also linked to insulin resistance, when cells in your muscles, fat, and liver don’t respond well to insulin.

Having too much visceral fat may increase the risk of heart disease, diabetes, and stroke.

Your Body Mass Index Matters

Body mass index (BMI) is a number calculated from a person’s weight and height. Most health professionals rely on BMI to assess whether their patients are overweight (BMI of 25 or more) or have obesity (BMI of 30 or more). All adults who are overweight should talk to their doctor about getting tested for type 2 diabetes.

People of Asian heritage in the normal weight range may have too much visceral fat and be at risk of type 2 diabetes at a lower BMI. Researchers now suggest that people of Asian heritage get tested if their BMI is 23 or more.

You Can Prevent Type 2 Diabetes

Before developing type 2 diabetes, most people have prediabetes, where blood sugar levels are higher than normal, but not high enough yet to be diagnosed as type 2 diabetes. People who have prediabetes are at increased risk of developing type 2 diabetes.

If you have prediabetes, losing a small amount of weight if you’re overweight and getting regular physical activity can lower your risk for developing type 2 diabetes. A lifestyle change program offered through the CDC-led National Diabetes Prevention Program can help you make those changes—and make them stick. Through the program, you can lower your risk of developing type 2 diabetes by as much as 58% (71% if you’re aged 60 years or older).

Take the 1-minute test to see if you may be at risk of prediabetes.

Managing Diabetes

If you have diabetes, getting support and education is critical. Diabetes self-management education and support (DSMES) services can help you stay healthy and thrive with diabetes.

Through DSMES, you’ll get to work one-on-one with a diabetes care and education specialist, a certified professional who is specially trained in diabetes care and management. They can:

  • Help you learn how to manage your blood sugar.
  • Explain how diabetes medicines work.
  • Help you figure out the best type of blood sugar monitoring device for you and your situation.
  • Suggest tools to help you track your progress.
  • Help you reduce your risks for complications.

Learn more about DSMES services.

Page last reviewed: June 22, 2021