Type 1 Diabetes

Topic Overview

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This topic has general information about type 1 diabetes for people who do not have the disease. If you want to learn how to manage type 1 diabetes, one of the following topics may meet your needs:

If you are looking for information about type 2 diabetes, see the topic Type 2 Diabetes.

What is type 1 diabetes?

Type 1 diabetes is a disease that starts when the pancreas stops making insulin. Insulin lets blood sugar—also called glucose—enter the body's cells to be used for energy. Without insulin, the cells can't get the sugar they need, and too much sugar builds up in the blood.

Diabetes can cause sudden or long-term problems. If the body doesn't have enough insulin and the blood sugar gets very high, a sudden and very serious problem called diabetic ketoacidosis can happen. This can be deadly. Over time, high blood sugar can damage the eyes, heart, blood vessels, nerves, and kidneys.

Type 1 diabetes can occur at any age, but it usually starts in children or young adults. That’s why it used to be called juvenile diabetes.

Type 1 diabetes is different from type 2 diabetes, which is the most common form of the illness. In type 1, the body stops making insulin. In type 2, the body does not make enough insulin, or the body can't use insulin the right way. All people with type 1 diabetes need to take insulin. Some people with type 2 diabetes also need insulin, but most people can use diet, exercise, and medicine in pills to treat that illness.

There isn't a cure for type 1 diabetes. But with treatment, people can live long and healthy lives.

What causes type 1 diabetes?

The body makes insulin in beta cells, which are in a part of the pancreas called the islet (say “EYE-let”) tissue. Type 1 diabetes starts because the body destroys the beta cells. Experts don't know why this happens.

Some people have a greater chance of getting type 1 diabetes, because they have a parent, brother, or sister who has it. But most people with the illness don't have a family history of it.

Other things that increase the risk of getting type 1 diabetes are being white and having islet cell antibodies in the blood.

What are the symptoms?

Symptoms of diabetes are:

  • Being very thirsty.
  • Urinating a lot.
  • Losing weight without trying.
  • Being hungrier than usual (sometimes).

These symptoms usually appear over a few days to weeks. Sometimes people notice symptoms after an illness, such as the flu. They may think that the diabetes symptoms are because of the flu, so they don't seek medical care soon enough.

If a person waits too long to get medical care, he or she may get symptoms of diabetic ketoacidosis. Symptoms of this problem include:

  • Flushed, hot, dry skin.
  • Not feeling hungry.
  • Belly pain.
  • Vomiting.
  • A strong, fruity breath odor.
  • Fast and shallow breathing.
  • Restlessness, drowsiness, or trouble waking up.
  • Confusion.

How is type 1 diabetes diagnosed?

A doctor asks questions about the person’s health and does a physical exam. A blood test measures the person’s glucose.

Some people are diagnosed with type 1 diabetes because they have symptoms of diabetic ketoacidosis.

How is it treated?

Treatment for type 1 diabetes focuses on keeping blood sugar levels within a target range. A person with type 1 diabetes needs to:

  • Take insulin through daily shots or an insulin pump.
  • Eat a healthy diet that spreads carbohydrate throughout the day.
  • Check blood sugar levels several times a day.
  • Get regular exercise.

When a small child has diabetes, the parents have the responsibility for blood sugar control. As the child grows, he or she can take over more of the diabetes care.

Treatment may change based on the results of daily home blood sugar tests and other tests or exams.

Can type 1 diabetes be prevented?

There is no way to prevent type 1 diabetes. But studies are being done to find ways to prevent or delay diabetes in people who are most likely to get it.

Tight control of blood sugar and blood pressure can help people with type 1 diabetes prevent or delay problems with their eyes, kidneys, heart, blood vessels, and nerves.

Frequently Asked Questions

Learning about type 1 diabetes:

Being diagnosed:

Getting treatment:

Ongoing concerns:

Living with type 1 diabetes:


Type 1 diabetes develops because the body's immune system destroys the beta cells which are in the islet tissue in the pancreas. These beta cells produce insulin. So people with type 1 diabetes cannot make their own insulin.

You can inherit a tendency to develop type 1 diabetes, but most people who have the disease have no family history of it. Diabetes experts believe that a genetic tendency and some environmental factors may increase the risk of developing type 1 diabetes. Possible environmental factors include enteroviral infections—especially Coxsackie B infections.

Despite concerns about vaccines (particularly those against whooping cough and Haemophilus influenza B, or Hib), studies have not found a relationship between being vaccinated and developing type 1 diabetes.1


Symptoms of type 1 diabetes usually develop quickly, over a few days to weeks, and are caused by blood sugar levels rising above the normal range (hyperglycemia). Early symptoms may be overlooked, especially if the person has recently had an illness, such as influenza (flu). Early symptoms include:

  • Frequent urination, which may be more noticeable at night. Some young children who have learned to use the toilet may start wetting the bed during naps or at night.
  • Extreme thirst and a dry mouth.
  • Weight loss.
  • Increased hunger (possibly).

Sometimes the blood sugar level rises excessively before a person knows something is wrong. Because insulin is not available, the cells in the body are unable to get the sugar (glucose) they need for energy. The body begins to break down fat and muscle for energy. When fat is used for energy, ketones—or fatty acids—are produced and enter the bloodstream, causing the chemical imbalance diabetic ketoacidosis. This is a life-threatening condition. Symptoms of diabetic ketoacidosis are:

  • Flushed, hot, dry skin.
  • Loss of appetite, abdominal pain, and vomiting.
  • A strong, fruity breath odor.
  • Rapid, deep breathing.
  • Restlessness, drowsiness, difficulty waking up, confusion, or coma. Young children may lack interest in their normal activities.

What Happens

Type 1 diabetes develops because the body destroys the beta cells in the islet tissue of the pancreas that produce insulin. The rate at which the beta cells are destroyed varies. Infants and children usually develop the disease suddenly because the beta cells are destroyed rapidly. Adults tend to develop the disease slowly because the beta cells are destroyed gradually.

Sometimes people notice diabetes symptoms after an illness, such as the flu. If they do not seek medical care quickly, the lack of insulin can cause the blood sugar level to rise much higher than normal. The body then uses fat and muscle for energy, which causes the release of ketones, or fatty acids. Ketones can lead to a chemical imbalance called diabetic ketoacidosis. It is a medical emergency. Symptoms of diabetic ketoacidosis include confusion; strong, fruity breath; and drowsiness, or even coma.

Sometimes after receiving initial treatment for type 1 diabetes, people have a period of time—from a few weeks to a few months—when the pancreas is again able to produce insulin. This is often called the "honeymoon period." At this time, a person may need to take little or no insulin, depending on how much insulin the pancreas produces. When the honeymoon period is over, the person needs to take insulin for the rest of his or her life.

Every person who has type 1 diabetes requires treatment designed for his or her needs. Treatment involves:

People with type 1 diabetes often have blood sugar levels outside of their target range. These out-of-range levels happen because injections of insulin cannot control blood sugar as smoothly as natural insulin made by your body. Blood sugar below a normal range (hypoglycemia) can develop quickly and lead to an emergency in only a few minutes. On the other hand, high blood sugar levels (hyperglycemia) usually develop slowly over hours or days. If blood sugar levels continue to rise, diabetic ketoacidosis can develop.

Over time, diabetes can damage the body's tissues. Persistent high blood sugar can damage the eyes (diabetic retinopathy), kidneys (diabetic nephropathy), nerves (diabetic neuropathy), and heart (leading to heart attacks). It also can damage blood vessels, leading to strokes and blockage of other arteries, especially in the legs. People who keep their blood sugar levels within a target range often can prevent—or at least delay—these complications. But some people still develop complications even with good blood sugar control.

People who work closely with their doctors and follow their prescribed treatment usually feel better and more in control of their lives.

Planning pregnancy when you have type 1 diabetes

Women who want to plan a pregnancy need to talk to their doctors about making sure they have good control of their blood sugar. Higher-than-normal blood sugar levels during the first trimester of pregnancy raise the risk of birth defects. Good care of diabetes before conception appears to reduce the risk of birth defects.

Women with diabetes who do not want to be become pregnant should use birth control. This reduces the risk of birth defects in unplanned pregnancies.

More Information:

What Increases Your Risk

Risk factors for type 1 diabetes include:

  • Family history of type 1 diabetes. Having a family history of the disease increases the chance that a person will have islet cell antibodies, but it does not predict that a person will have the disease. Only about 10% to 15% of people with type 1 diabetes have a family history of the disease.1
    • If the father has the disease, a child has a 6% risk of developing it.
    • If a sibling has the disease, a child has a 5% risk of developing it.
    • If the mother has the disease, a child has a 2% risk of developing it.
    • If an identical twin has the disease, the other twin has a 30% to 50% risk of developing it.
    • If a parent and one sibling have the disease, a child has a 30% risk of developing it.
  • Race. White people have a greater risk for developing type 1 diabetes than black, Asian, or Hispanic people.
  • Presence of islet cell antibodies in the blood. People who have both a family history of type 1 diabetes and islet cell antibodies in their blood are likely to develop the disease at some time.

More Information:

When To Call a Doctor

Call 911 or other emergency services immediately if you or your child is:

Call a doctor immediately if you or your child is vomiting and cannot keep down liquids and:

  • Your blood sugar is 300 mg/dL or higher.
  • Your child’s blood sugar is 250 mg/dL or higher.

Call a doctor if you or your child:

  • Has increased urination, increased thirst, weight loss, and possibly increased appetite. These symptoms may indicate type 1 diabetes.
  • Has a family history of type 1 diabetes and wants to be tested.

Watchful Waiting

Watchful waiting is a period of time during which you and your doctor observe your symptoms or condition without using medical treatment. Watchful waiting is not appropriate if you think you or your child may have symptoms of type 1 diabetes, such as increased urination, increased thirst, weight loss, and possibly increased appetite. A blood test is all that is needed to determine whether a person has the disease.

Who To See

The following health professionals can diagnose and treat diabetes:

To prepare for your appointment, see the topic Making the Most of Your Appointment.

Exams and Tests

Many people are not diagnosed with type 1 diabetes until they are admitted to a hospital for diabetic ketoacidosis (DKA). This life-threatening condition occurs when ketones, or fatty acids, are produced as the body burns fat and muscle instead of glucose for fuel. DKA develops in people who have type 1 diabetes (and some people who have type 2 diabetes) when their blood sugar is very high.

During hospitalization, people with DKA will be watched closely and receive tests to measure the levels of electrolytes and sugar (glucose) in their blood.

If a person is not in ketoacidosis, the American Diabetes Association's criteria for symptoms, a medical history, a physical examination, and blood tests are used to diagnose type 1 diabetes.

These blood tests include:

  • Hemoglobin A1c, a test that estimates your blood sugar over the past 2 to 3 months.
  • Blood glucose test, a test that measures your blood sugar. This test is done preferably after fasting, but it can be done at any time, even if you have recently eaten.

Other tests that may suggest diabetes

You may need a thyroid-stimulating hormone (TSH) test when type 1 diabetes is diagnosed and then every 1 to 2 years. This test checks for thyroid problems, which are common among people with diabetes.

Neither a home blood sugar test nor a urine test for sugar is recommended to screen for or diagnose diabetes.

Early Detection

Screening for type 1 diabetes is not recommended by the American Diabetes Association. Such screening would include testing everyone for islet cell antibodies. This test can show if a person is more likely to get type 1 diabetes.

People who are found to have islet cell antibodies may be able to participate in studies about preventing type 1 diabetes. These people need to be referred to a medical center conducting a type 1 diabetes prevention study.2

Treatment Overview

Treatment for adults

Type 1 diabetes requires lifelong treatment to keep blood sugar levels within a target range. Treatment includes:

  • Taking several insulin injections every day or using an insulin pump.
  • Monitoring blood sugar levels several times a day using a home blood sugar meter.
  • Eating a healthful diet that spreads carbohydrate throughout the day, to prevent high blood sugar levels after meals.
  • Regular physical exercise, because exercise helps the body to use insulin more efficiently. Exercise may also lower your risk for heart and blood vessel disease.
  • Regular medical checkups to monitor and adjust treatment as needed. Screening tests and exams need to be done regularly to watch for signs of complications, such as eye, kidney, heart, blood vessel, and nerve diseases.
  • Not smoking.
  • Not drinking alcohol if the person is at risk for periods of low blood sugar.

A regular daily schedule makes managing blood sugar levels easier. Blood sugars are easier to predict and control when mealtimes, amounts of food, and exercise are similar every day.

Many people find out that they have type 1 diabetes when they are admitted to a hospital for diabetic ketoacidosis. If their symptoms are severe, they may need to be treated in an intensive care unit. Treatment for diabetic ketoacidosis includes fluids given through a vein (intravenous, or IV) to treat dehydration and to balance electrolytes, and insulin to lower the blood sugar level and stop the body from producing ketones.3

Treatment for children

Treatment for children includes all of the above measures to keep blood sugar levels within the child's target range. Treatment for children should also allow for normal growth and development. See the topics Type 1 Diabetes: Recently Diagnosed and Type 1 Diabetes: Children Living With the Disease.

When a small child has diabetes, the parents have the responsibility for blood sugar control. As the child grows, he or she can take more responsibility for diabetes care.


Preventing type 1 diabetes

Currently there is no way to prevent type 1 diabetes, but ongoing studies are exploring ways to prevent diabetes in those who are most likely to develop it. People who have a parent, brother, or sister with type 1 diabetes and are willing to participate in one of these studies should talk with their doctors. They may want to be tested for islet cell antibodies, because if they have these antibodies, they are more likely to get diabetes.

Vaccines have not been found to contribute to the development of type 1 diabetes.4 Children who are at risk for developing diabetes still need to get the recommended immunizations. See the childhood immunization schedule recommended by the U.S. Advisory Committee on Immunization Practices, the American Academy of Pediatrics, and the American Academy of Family Physicians.

Preventing diabetes complications

People with type 1 diabetes can help prevent or delay the development of complications by keeping their blood sugar in a target range. They also need regular medical checkups to detect early signs of complications. If complications are treated early, the damage may be stopped, slowed, or possibly reversed.

People who have other health problems along with diabetes, such as high blood pressure or high cholesterol, need to treat those conditions. Also, not smoking can reduce the risk of complications. Having other health problems can increase the risk for complications from diabetes.

Preventing flu and pneumococcal disease

People who have diabetes should have a flu shot every year and a pneumococcal vaccine. Usually, people need only one dose of the pneumococcal vaccine. But doctors sometimes recommend a second dose for some people, especially if they have a long-term disease. Talk with your doctor about whether you need a second dose. The pneumococcal vaccine helps prevent infections caused by pneumococcal bacteria. People with diabetes, especially those who have heart or kidney disease, are at high risk for complications, hospitalization, and death from flu and pneumococcal disease.5

Home Treatment

People who have type 1 diabetes need to work closely with their doctors to find the right balance of diet, insulin, and exercise to keep their blood sugar levels within a target range. That combination will vary over time, especially for children.

Daily treatment for diabetes includes:

Other steps to take

People with type 1 diabetes also need to:

  • Wear medical identification at all times so that, in case of emergency, health professionals can see that they have diabetes.
  • Treat high and low blood sugar levels quickly to prevent an emergency.
  • Take extra care of their feet, gums, and teeth to prevent problems that may develop because of high blood sugar.
  • Know how to adjust their diet or insulin doses when they are sick or when they become pregnant.
  • Have regular medical checkups to monitor the disease and adjust treatment as needed.


A person who has type 1 diabetes must take insulin every day because his or her pancreas does not produce it. Insulin helps blood sugar (glucose) enter the body's cells to be used for energy. Insulin can be given as an injection into the fatty tissue under the skin or through an insulin pump.

Usually people with type 1 diabetes take a combination of types of insulin, such as a long-acting insulin once or twice a day and a rapid-acting insulin before each meal. The amount and type of insulin needed varies for each person. Also, the amount and type of insulin needed changes over time, depending on age, hormones (such as during rapid growth or pregnancy), and changes in exercise routine. In addition, a person may need higher doses of insulin during times of illness or emotional stress.

Other medicines may be needed if a person develops complications from diabetes, such as kidney disease.

A person also may need medicines to treat high blood pressure or high cholesterol and help prevent complications from diabetes. Talk to your doctor about whether you should take low dose aspirin. Daily low dose aspirin (81 milligrams) may help prevent heart problems if you are at risk for heart attack or stroke.


Surgery for type 1 diabetes is done only in special situations.

  • Surgery to replace the pancreas (pancreas transplant) may be done when a person is receiving another organ, such as a kidney.
  • Surgery to insert working pancreas cells (islet cell transplant) is experimental.

These surgeries are very expensive. After having one of these surgeries, a person must take medicine for the rest of his or her life to prevent the body from rejecting the new tissue (immunosuppression medicines).

Other Treatment

People who have type 1 diabetes need to avoid products that promise a “cure.” No cure exists. They also need to avoid products for diabetes that are advertised by testimonials without a sound medical basis. These products or remedies may be harmful and costly. They also might cause people to delay or avoid getting other forms of treatment that have been proved to work.

Other Places To Get Help


American Diabetes Association (ADA)
1701 North Beauregard Street
Alexandria, VA  22311
Phone: 1-800-DIABETES (1-800-342-2383)
E-mail: AskADA@diabetes.org
Web Address: www.diabetes.org

The American Diabetes Association (ADA) is a national organization for health professionals and consumers. Almost every state has a local office. ADA sets the standards for the care of people with diabetes. Its focus is on research for the prevention and treatment of all types of diabetes. ADA provides patient and professional education mainly through its publications, which include the monthly magazine Diabetes Forecast, books, brochures, cookbooks and meal planning guides, and pamphlets. ADA also provides information for parents about caring for a child with diabetes.

Juvenile Diabetes Research Foundation International
120 Wall Street
New York, NY  10005-4001
Phone: 1-800-533-CURE (1-800-533-2873)
Fax: (212) 785-9595
E-mail: info@jdrf.org
Web Address: http://www.jdrf.org

The Juvenile Diabetes Research Foundation International is dedicated to finding a cure for type 1 diabetes and its complications. The organization funds research on type 1 diabetes, including research on prevention and treatment. This organization publishes a wide variety of booklets, magazines, and e-newsletters on complications and treatments of type 1 diabetes.

National Diabetes Education Program (NDEP)
1 Diabetes Way
Bethesda, MD  20814-9692
Phone: 1-800-438-5383 to order materials
(301) 496-3583
E-mail: ndep@mail.nih.gov
Web Address: http://ndep.nih.gov

The National Diabetes Education Program (NDEP) is sponsored by the U.S. National Institutes of Health (NIH) and the U.S. Centers for Disease Control and Prevention (CDC). The program's goal is to improve the treatment of people who have diabetes, to promote early diagnosis, and to prevent the development of diabetes. Information about the program can be found on two Web sites: one managed by NIH (http://ndep.nih.gov) and the other by CDC (www.cdc.gov/team-ndep).

National Diabetes Information Clearinghouse (NDIC)
1 Information Way
Bethesda, MD  20892-3560
Phone: 1-800-860-8747
Fax: (703) 738-4929
TDD: 1-866-569-1162 toll-free
E-mail: ndic@info.niddk.nih.gov
Web Address: http://diabetes.niddk.nih.gov

This clearinghouse provides information about research and clinical trials supported by the U.S. National Institutes of Health. This service is provided by the National Institute of Diabetes and Digestive and Kidney Disease (NIDDK), a part of the National Institutes of Health (NIH).



  1. Lawson ML, Muirhead SE (2001). What is type 1 diabetes? In HC Gerstein, RB Haynes, eds., Evidence-Based Diabetes Care, pp. 124–150. Hamilton, ON: BC Decker.
  2. American Diabetes Association (2004). Prevention of type 1 diabetes mellitus. Clinical Practice Recommendations 2004. Diabetes Care, 27(Suppl 1): S133.
  3. American Diabetes Association (2004). Hyperglycemic crises in diabetes. Clinical Practice Recommendations 2004. Diabetes Care, 27(Suppl 1): S94–S102.
  4. Hviid A, et al. (2008). Childhood vaccination and type 1 diabetes. New England Journal of Medicine, 350(14): 1398–1404.
  5. American Diabetes Association (2004). Influenza and pneumococcal immunization in diabetes. Clinical Practice Recommendations 2004. Diabetes Care, 27(Suppl 1): S111–S113.

Other Works Consulted

  • American Diabetes Association (2006). Pancreas and islet transplantation in type 1 diabetes. Position statement. Diabetes Care, 29(4): 935.
  • Genuth S (2008). Type 1 diabetes mellitus. In DC Dale, DD Federman, eds., ACP Medicine, section 9, chap. 1. New York: WebMD.
  • Pickup J, Keen H (2002). Continuous subcutaneous insulin infusion at 25 years. Diabetes Care, 25(30): 593–598.
  • White SA, et al. (2001). Human islet cell transplantation: Future prospects. Diabetic Medicine, 18(2): 78–103.


Author Judy Dundas
Editor Susan Van Houten, RN, BSN, MBA
Associate Editor Pat Truman, MATC
Primary Medical Reviewer Caroline S. Rhoads, MD - Internal Medicine
Specialist Medical Reviewer Matthew I. Kim, MD - Endocrinology & Metabolism
Last Updated September 17, 2008

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