Type 2 Diabetes: The Basics

Diabetes is a life-long disease that affects the way your body handles glucose, a kind of sugar, in your blood.

Most people with the condition have type 2. There are about 27 million people in the U.S. with it. Another 86 million have prediabetes: Their blood glucose is not normal, but not high enough to be diabetes yet.

What Causes Diabetes?

Your pancreas makes a hormone called insulin. It's what lets your cells turn glucose from the food you eat into energy. People with type 2 diabetes make insulin, but their cells don't use it as well as they should. Doctors call this insulin resistance.

At first, the pancreas makes more insulin to try to get glucose into the cells. But eventually it can't keep up, and the sugar builds up in your blood instead.

Usually a combination of things cause type 2 diabetes, including:

Genes. Scientists have found different bits of DNA that affect how your body makes insulin.

Extra weight. Being overweight or obese can cause insulin resistance, especially if you carry your extra pounds around the middle. Now type 2 diabetes affects kids and teens as well as adults, mainly because of childhood obesity.

Metabolic syndrome. People with insulin resistance often have a group of conditions including high blood glucose, extra fat around the waist, high blood pressure, and high cholesterol and triglycerides.

Too much glucose from your liver. When your blood sugar is low, your liver makes and sends out glucose. After you eat, your blood sugar goes up, and usually the liver will slow down and store its glucose for later. But some people's livers don't. They keep cranking out sugar.

Bad communication between cells. Sometimes cells send the wrong signals or don't pick up messages correctly. When these problems affect how your cells make and use insulin or glucose, a chain reaction can lead to diabetes.

Broken beta cells. If the cells that make the insulin send out the wrong amount of insulin at the wrong time, your blood sugar gets thrown off. High blood glucose can damage these cells, too.


Risk Factors and Prevention

While certain things make getting diabetes more likely, they won't give you the disease. But the more that apply to you, the higher your chances of getting it are.

Some things you can't control.

  • Age: 45 or older
  • Family: A parent, sister, or brother with diabetes
  • Ethnicity: African-American, Alaska Native, Native American, Asian-American, Hispanic or Latino, or Pacific Islander-American

Some things are related to your health and medical history. Your doctor may be able to help.

  • Prediabetes
  • Heart and blood vessel disease
  • High blood pressure, even if it's treated and under control
  • Low HDL ("good") cholesterol
  • High triglycerides
  • Being overweight or obese
  • Having a baby that weighed more than 9 pounds
  • Having gestational diabetes while you were pregnant
  • Polycystic ovary syndrome (PCOS)
  • Acanthosis nigricans, a skin condition with dark rashes around your neck or armpits
  • Depression

Other risk factors have to do with your daily habits and lifestyle. These are the ones you can really do something about.

Because you can't change what happened in the past, focus on what you can do now and going forward. Take medications and follow your doctor's suggestions to be healthy. Simple changes at home can make a big difference, too.

Lose weight. Dropping just 7% to 10% of your weight can cut your risk of type 2 diabetes in half.

Get active. Moving muscles use insulin. Thirty minutes of brisk walking a day will cut your risk by almost a third.

Eat right. Avoid highly processed carbs, sugary drinks, and trans and saturated fats. Limit red and processed meats.

Quit smoking. Work with your doctor to avoid gaining weight, so you don't create one problem by solving another.


The symptoms of type 2 diabetes can be so mild you don't notice them. In fact, about 8 million people who have it don't know it.

  • Being very thirsty
  • Peeing a lot
  • Blurry vision
  • Being irritable
  • Tingling or numbness in your hands or feet
  • Feeling worn out
  • Wounds that don't heal
  • Yeast infections that keep coming back


Getting a Diagnosis

Your doctor can test your blood for signs of diabetes. Usually doctors will test you on two different days to confirm the diagnosis. But if your blood glucose is very high or you have a lot of symptoms, one test may be all you need.

A1C: It's like an average of your blood glucose over the past 2 or 3 months.

Fasting plasma glucose: This measures your blood sugar on an empty stomach. You won't be able to eat or drink anything except water for 8 hours before the test.

Oral glucose tolerance test (OGTT): This checks your blood glucose before and 2 hours after you drink a sweet drink to see how your body handles the sugar.

Long-Term Effects

Over time, high blood sugar can damage and cause problems with your:

  • Heart and blood vessels
  • Kidneys
  • Eyes
  • Nerves, which can lead to trouble with digestion, the feeling in your feet, and your sexual response
  • Wound healing
  • Pregnancy

The best way to avoid these complications is to manage your diabetes well.

  • Take your diabetes medications or insulin on time.
  • Check your blood glucose.
  • Eat right, and don't skip meals.
  • See your doctor regularly to check for early signs of trouble.


WebMD Medical Reference Reviewed by Michael Dansinger, MD on June 22, 2015



American Diabetes Association: "Statistics About Diabetes," "Type 1 Diabetes," "Type 2," "Diagnosing Diabetes and Learning About Prediabetes."

U.S. National Library of Medicine: "Diabetes in Children and Teens."

Cleveland Clinic: "Diabetes Learning Module," "Preventing Diabetes Complications."

National Diabetes Information Clearinghouse: "Causes of Diabetes."

International Diabetes Federation: "Prevention," "Complications of Diabetes."

Harvard T.H. Chan School of Public Health: "Simple Steps to Preventing Diabetes."

National Institute of Diabetes and Digestive and Kidney Diseases: "Am I at risk for type 2 diabetes?"

Joslin Diabetes Center: "Common Questions About Type 2 Diabetes."

Carolinas HealthCare System: "Yeast Infections and Diabetes: What You Should Know."

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