What is Diabetes, type 2?

Diabetes, type 2

What is type 2 diabetes?

If you have diabetes, you have too much glucose in your blood. Glucose is a kind of sugar your body uses for energy. If it builds up in your blood it can make you sick.

Diabetes doesn't go away. And if you don't treat it, you can get serious health problems. If you change the way you live, take medication and watch your condition closely, you can keep your glucose levels under control. You should be able to live a long and healthy life.

Key points for people with diabetes

Diabetes is a serious condition. But with the right treatment, you should be able to stay healthy.
If you have diabetes, you have too much glucose in your blood.
There are two main types of diabetes: type 1 and type 2 (see below).
Many people with diabetes don't know they have it. They might not have any symptoms, or they might think the symptoms they do have aren't important. If you have symptoms like feeling very thirsty, hungry or tired, blurry vision or needing to urinate a lot, don't ignore them.

Over time, high levels of glucose in your blood can damage your blood vessels. This can lead to problems in your heart, eyes,

kidney
Your kidneys are organs that filter your blood to make urine. You have two of them, on either side of your abdominal cavity, toward your back.

kidneys and other parts of your body.
If you keep your blood glucose level as close to normal as possible, you might be able to avoid some of these problems.
It's not easy to keep your blood glucose under control. And if you don't feel sick, you might not want to think about your glucose level. But keeping it under control is important for staying healthy.

What's a normal glucose level?

You always need to have some glucose in your blood. It comes from food and it gives your body energy. Every cell in your body needs glucose to work properly.

Diabetes is a long-term condition, but with the right treatment you can live a long and healthy life.

Normally, the amount of glucose in your blood is carefully controlled by a chemical called insulin. Insulin is a

hormones
Hormones are chemicals that are made in certain parts of the body. They travel through the bloodstream and have an effect on other parts of the body. For example, the female sex hormone estrogen is made in a woman's ovaries. Estrogen has many different effects on a woman's body. It makes the breasts grow at puberty and helps control periods. It is also needed to get pregnant.

hormone made by your pancreas, a

gland
A gland is any group of cells in the body that makes and releases something for use by another part of the body. For example, the thyroid gland makes a hormone called thyroxine. This acts on receptors within cells. By acting on the receptors it gives the cells a message to speed up their metabolism and work harder.

gland that sits behind your stomach. Insulin helps move glucose from your blood into your body's cells. Your cells use the glucose as energy. Insulin keeps your blood levels of glucose steady.

Doctors measure how much glucose is in your blood in milligrams per deciliter. The short version is mg/dL.

In people who don't have diabetes, the amount of glucose in their blood is between 70 mg/dL and about 120 mg/dL.

Source:
National Diabetes Information Clearinghouse (NDIC).
Your guide to diabetes: type 1 and type 2.
October 2006. National Institute of Diabetes and Digestive and Kidney Diseases. Available at http://diabetes.niddk.nih.gov (accessed on 10 December 2008).

¹ Your doctor might talk about your blood glucose level using just the number. For example, your doctor might say, "Your blood glucose is 120."

Normally, your blood glucose level goes up and down throughout the day. Before breakfast, a normal level is less than 100 mg/dL.

Types of diabetes

There are two main types of diabetes: type 1 and type 2.

Type 1 diabetes usually starts in adolescence.
Type 2 comes on gradually, usually when you're 40 or over.
There's also a condition called impaired glucose tolerance. This isn't diabetes, but it does increase your chances of getting diabetes.
Some women get a kind of diabetes while they're pregnant. This is called gestational diabetes.

This information is for people with type 2 diabetes. For more information about other types of diabetes, see:

Type 2 diabetes

Most people who have diabetes get type 2 diabetes.

Source:
Centers for Disease Control and Prevention.
Diabetes: disabling disease to double by 2050.
September 2008. Available at http://www.cdc.gov/nccdphp/publications/aag/ddt.htm (accessed on 11 December 2008).

² More than 90 percent of people with diabetes have this type.

It usually starts later in life and is more common in people who are

obesity
If your body stores more energy than you need for daily functioning, this can make you overweight. The excess energy is stored in your fat cells. If your weight goes above a certain level, doctors call this obesity. Obesity is considered a medical condition. The excess weight can be a strain on your bones and joints. And if you are obese, you're more likely to get other diseases. Doctors have developed a scale for telling how much excess weight you have. This measure, called the body mass index (BMI), depends on your height.

obese. But type 2 diabetes is getting more common in children. This is because more children are overweight today than in the past.

Type 2 diabetes used to be called non-insulin-dependent diabetes mellitus (or NIDDM for short) because people who have type 2 diabetes often don't need to take

insulin
Insulin is a hormone that helps your body use glucose, a type of sugar that gives you energy. Insulin keeps your levels of glucose steady. It also helps glucose get into your cells from your blood. People who have diabetes do not have enough insulin or do not react to insulin strongly enough. This leads to too much glucose in their blood.

insulin. It's sometimes called adult-onset diabetes because it tends to start in people over 40.

What happens in type 2 diabetes?

If you have diabetes, your body can't control how much glucose is in your blood. Instead of the glucose being gradually used up as fuel by your cells, it builds up in your blood. You'll hear the word hyperglycemia a lot. It means having too much glucose in your blood. To find out how this affects you, see What are the symptoms of type 2 diabetes?

You need insulin to keep your glucose level under control. In diabetes, your glucose level can get too high for different reasons.

Your body may not be making enough insulin. It might make only a little or none at all.
Your body may be making insulin but the insulin isn't working properly. Scientists think that your cells don't behave as they should when insulin reaches them. Doctors call this insulin resistance.
One of insulin's jobs is to tell cells in your

liver
Your liver is a large organ that sits on the right side of your body, just below your rib cage. It does several important things, including processing and storing nutrients from food, and breaking down chemicals, such as alcohol.

liver how to use glucose. If there's any extra glucose in your blood, it should be stored in your liver. But if you have type 2 diabetes, your liver cells don't get the right messages. So instead of storing the glucose, your liver pumps more glucose into your blood.

Why me?

Certain things can increase your chances of getting a disease. Doctors call these things risk factors. Having a risk factor for diabetes doesn't mean you will get the disease for sure. It just means you are more likely to get diabetes than someone who doesn't have that risk factor.

Here are some risk factors for type 2 diabetes.

Having a relative with type 2 diabetes: You're more likely to get type 2 diabetes if someone in your family has it. Your

genes
Your genes are the parts of your cells that contain instructions for how your body works. Genes are housed on chromosomes, structures that sit in the nucleus at the middle of each of your cells. You have 23 pairs of chromosomes in your normal cells, each of which has thousands of genes. You get one set of chromosomes, and all of the genes that are on them, from each of your parents.

genes play a role. If both of your parents have type 2 diabetes, you have a 1 in 2 chance of getting it.

Source:
American Diabetes Association.
The genetics of diabetes.
Available at http://www.diabetes.org/genetics.jsp (accessed on 8 December 2008).

³ (To find out more about what these numbers mean, see Understanding risks.)
Being obese: Some people believe that eating too much sugar causes diabetes. They think this extra sugar wears out your

pancreas
Your pancreas is an organ that's behind your stomach. It makes several different chemicals. Some of the chemicals help your body digest food. Your pancreas also makes a chemical called insulin, which helps your body use the sugar in your blood.

pancreas. This isn't true.

Source:
Diabetes UK.
Causes and risk factors.
Available at http://www.diabetes.org.uk/Guide-to-diabetes (accessed on 10 December 2008).

⁴ What matters is your weight. Obesity is the main risk factor for type 2 diabetes.
Lack of exercise: About 80 percent of people with type 2 diabetes are overweight and don't get enough exercise. If you're at risk for this type of diabetes, you can reduce your risk if you exercise. For example, if you're overweight and you lose about 5 percent of your body weight, and you also get regular, moderate exercise (such as a brisk walk for 30 minutes, five days a week), your chance of getting diabetes is cut by one-half.

Source:
Knowler WC, Barrett-Connor E, Fowler SE, et al.
Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin.
New England Journal of Medicine. 2002; 346: 393-403.

⁵
Your ethnic background: African-Americans, Hispanic Americans, Asian-Americans, American Indians and Pacific Islanders are more likely to get type 2 diabetes than other Americans.

Source:
Centers for Disease Control and Prevention.
National diabetes fact sheet: general information and national estimates on diabetes in the United States.
2002. U.S. Department of Health and Human Services.

⁶ We're not sure why this is.
Factors related to pregnancy: If you are a woman, you are more likely to get type 2 diabetes if you give birth to a baby weighing more than 9 pounds or have diabetes during pregnancy.

Source:
Harris MI.
Gestational diabetes may represent discovery of preexisting glucose intolerance.
Diabetes Care. 1988; 11: 402-411.

⁷ For more information, see Other types of diabetes and high blood glucose.
Having a condition called the metabolic syndrome: People who have this condition are more likely to get type 2 diabetes. For more, see The metabolic syndrome.

Sources for the information on this page:

National Diabetes Information Clearinghouse (NDIC).Your guide to diabetes: type 1 and type 2.October 2006. National Institute of Diabetes and Digestive and Kidney Diseases. Available at http://diabetes.niddk.nih.gov (accessed on 10 December 2008).

Centers for Disease Control and Prevention.Diabetes: disabling disease to double by 2050.September 2008. Available at http://www.cdc.gov/nccdphp/publications/aag/ddt.htm (accessed on 11 December 2008).

American Diabetes Association.The genetics of diabetes.Available at http://www.diabetes.org/genetics.jsp (accessed on 8 December 2008).

Diabetes UK.Causes and risk factors.Available at http://www.diabetes.org.uk/Guide-to-diabetes (accessed on 10 December 2008).

Knowler WC, Barrett-Connor E, Fowler SE, et al.Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin.New England Journal of Medicine. 2002; 346: 393-403.

Centers for Disease Control and Prevention.National diabetes fact sheet: general information and national estimates on diabetes in the United States.2002. U.S. Department of Health and Human Services.

Harris MI.Gestational diabetes may represent discovery of preexisting glucose intolerance.Diabetes Care. 1988; 11: 402-411.

This information was last updated on May 11, 2009

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