Type 2 Diabetes Causes and Risk Factors

Causes of Type 2 Diabetes

While not everyone with type 2 diabetes is overweightobesity and an inactive lifestyle are two of the most common causes of type 2 diabetes. It is also responsible for about 90% to 95% of diabetes cases in the United States.

What Causes Type 2 Diabetes?

When you're healthy, the pancreas (an organ behind the stomach) releases insulin to help your body store and use sugar from the food you eat. Diabetes happens when one or more of the following occurs:

  • Your pancreas doesn't make any insulin.
  • Your pancreas makes very little insulin.
  • Your body doesn’t respond like it should to insulin

Unlike people with type 1 diabetes, people with type 2 diabetes make insulin. But the insulin their pancreas secretes either isn’t enough or their body can't recognize the insulin and use it properly (doctors call this insulin resistance).

When there isn't enough insulin or the insulin isn't used as it should be, glucose (sugar) can't get into your cells. It builds up in your bloodstream instead. This can damage many areas of the body. Also, since cells aren't getting the glucose they need, they don't work like they should.

Health Risk Factors for Type 2 Diabetes

Type 2 diabetes is believed to have a strong genetic link, meaning that it tends to run in families. Several genes may be related to type 2 diabetes. If you have any of the following risk factors, it’s important to ask your doctor about a diabetes test. A proper diet and healthy lifestyle habits, along with medication, if you need it, can help you manage type 2 diabetes just like you manage other areas of your life. Be sure to seek the latest information on this condition as you become your own health advocate.

Other type 2 diabetes risk factors include the following:

  • High blood pressure
  • High blood triglyceride (fat) levels
  • Gestational diabetes or giving birth to a baby weighing more than 9 pounds
  • High-fat and carbohydrate diet
  • High alcohol intake
  • Sedentary lifestyle
  • Obesity or being overweight
  • Ethnicity: Certain groups, such as African Americans, Native Americans, Hispanic Americans, and Asian Americans, have a greater risk of developing type 2 diabetes than non-Hispanic whites.
  • Aging: Increasing age is a significant risk factor for type 2 diabetes. The risk of developing type 2 diabetes begins to rise significantly at about age 45, and rises considerably after age 65.

 

 

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The Role of Insulin in the Cause of Type 2 Diabetes

To understand why insulin is important, it helps to know more about how your body uses food for energy. Your body is made up of millions of cells. To make energy, these cells need food in a very simple form. When you eat or drink, much of the food is broken down into a simple sugar called glucose. It moves through your bloodstream to these cells where it provides the energy your body needs for daily activities.

Insulin and other hormones control the amount of glucose in your bloodstream. Your pancreas is always releasing small amounts of insulin. When the amount of glucose in your blood rises to a certain level, the pancreas will release more insulin to push more glucose into the cells. This causes the glucose levels in the blood (blood glucose levels) to drop.

To keep blood glucose levels from getting too low (hypoglycemia or low blood sugar), your body signals you to eat and releases some glucose from the stores kept in the liver. It also tells the body to release less insulin..

People with diabetes either don't make insulin or their body's cells can no longer use their insulin. This leads to high blood sugars. By definition, diabetes is:

  • A blood glucose level of greater than or equal to 126 milligrams per deciliter of blood (mg/dL) after an 8-hour fast (not eating anything)
  • A non-fasting glucose level greater than or equal to 200 mg/dL along with symptoms of diabetes
  • A glucose level of greater than or equal to 200 mg/dL on a 2-hour glucose tolerance test
  • A1C greater than or equal to 6.5%. Unless the person is having obvious symptoms of diabetes or is in a diabetic crisis, the diagnosis must be confirmed with a repeat test.
WebMD Medical Reference Reviewed by Michael Dansinger, MD on May 26, 2019

Sources

SOURCES: 

American Diabetes Association: "Insulin and Low Blood Glucose." 

American Diabetes Association: "Stomach Fat and Insulin Resistance." 

National Diabetes Information Clearinghouse: "Your Guide to Diabetes:  Type 1 and Type 2." 

Forouhi, N. Diabetologia, 2006; 49:822. Kim, SH. Journal of the American College of Cardiology, 2006; 48:293. 

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