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Type 1 diabetes

Definition

Type 1 diabetes is a chronic (lifelong) disease that occurs when the pancreas does not produce enough insulin to properly control blood sugar levels.

See also:

Alternative Names

Insulin-dependent diabetes; Juvenile onset diabetes; Diabetes - type 1

Causes, incidence, and risk factors

There are several forms of diabetes. Type 1 diabetes used to be called juvenile or insulin-dependent diabetes. Type 1 diabetes can occur at any age, but it is most often diagnosed in children, adolescents, or young adults.

Insulin is a hormone produced by special cells, called beta cells, in the pancreas, an organ located in the area behind your stomach. Insulin is needed to move blood sugar (glucose) into cells, where it is stored and later used for energy. In type 1 diabetes, these cells produce little or no insulin.

Without enough insulin, glucose builds up in the bloodstream instead of going into the cells. The body is unable to use this glucose for energy. This leads to the symptoms of type 1 diabetes.

Within 5 - 10 years, the insulin-producing beta cells of the pancreas are completely destroyed and the body can no longer produce insulin.

The exact cause is unknown, but most likely there is a viral or environmental trigger in genetically susceptible people that causes an immune reaction. The body's white blood cells mistakenly attack the insulin-producing pancreatic beta cells.

Symptoms

Some people will have no symptoms before they are diagnosed with diabetes.

Others may notice these symptoms as the first signs of type 1 diabetes, or when the blood sugar is high:

  • Feeling tired or fatigued
  • Feeling hungry
  • Being very thirsty
  • Urinating more often
  • Losing weight without trying
  • Having blurry eyesight
  • Losing the feeling or feeling tingling in your feet

For others, warning symptoms that they are becoming very sick may be the first signs of type 1 diabetes, or may happen when the blood sugar is very high (see: diabetic ketoacidosis):

  • Deep, rapid breathing
  • Dry skin and mouth
  • Flushed face
  • Fruity breath odor
  • Nausea or vomiting, unable to keep down fluids
  • Stomach pain

Low blood sugar (hypoglycemia) can develop quickly in people with diabetes who are taking insulin. Symptoms typically appear when the blood sugar level falls below 70 mg/dL. Watch for:

  • Headache
  • Hunger
  • Nervousness
  • Rapid heartbeat (palpitations)
  • Shaking
  • Sweating
  • Weakness

Signs and tests

Diabetes is diagnosed with the following blood tests:

  • Fasting blood glucose level -- diabetes is diagnosed if it is higher than 126 mg/dL on two occasions
  • Random (nonfasting) blood glucose level -- diabetes is suspected if it is higher than 200 mg/dL, and the patient has symptoms such as increased thirst, urination, and fatigue (this must be confirmed with a fasting test)
  • Oral glucose tolerance test -- diabetes is diagnosed if the glucose level is higher than 200 mg/dL after 2 hours.
  • Hemoglobin A1c test -- this test has been used in the past to help patients monitor how well they are controlling their blood glucose levels. In 2010, the American Diabetes Association recommended that the test be used as another option for diagnosing diabetes and identifiying pre-diabetes. Levels indicate:
    • Normal: Less than 5.7%
    • Pre-diabetes: Between 5.7% and 6.4%
    • Diabetes: 6.5% or higher

Ketone testing is also used in type 1 diabetes. Ketones are produced by the breakdown of fat and muscle. They are harmful at high levels. The ketone test is done using a urine sample. Ketone testing is usually done at the following times:

  • When the blood sugar is higher than 240 mg/dL
  • During an illness such as pneumonia, heart attack, or stroke
  • When nausea or vomiting occur
  • During pregnancy

The following tests will help you and your doctor monitor your diabetes and prevent complications of diabetes:

  • Check the skin and bones on your feet and legs.
  • Check the sensation in your feet.
  • Have your blood pressure checked at least every year (blood pressure goal should be 130/80 mm/Hg or lower).
  • Have your glycosulated hemoglobin (HbA1c) checked every 6 months if your diabetes is well controlled; otherwise, every 3 months.
  • Have your cholesterol and triglyceride levels checked yearly (aim for LDL cholesterol levels below 70-100 mg/dL).
  • Get yearly tests to make sure your kidneys are working well (microalbuminuria and serum creatinine).
  • Visit your ophthalmologist at least once a year, or more often if you have signs of diabetic retinopathy.
  • See the dentist every 6 months for a thorough dental cleaning and exam. Make sure your dentist and hygienist know that you have diabetes.

Treatment

The immediate goals of treatment are to treat diabetic ketoacidosis and high blood glucose levels. Because type 1 diabetes can come on suddenly and the symptoms can be severe, newly diagnosed people may need to stay in the hospital.

The long-term goals of treatment are to:

  • Reduce symptoms
  • Prevent diabetes-related complications such as blindness, kidney failure, nerve damage, amputation of limbs, and heart disease

You are the most important person in managing your diabetes. You should know the basic steps to diabetes management:

  • How to recognize and treat low blood sugar (hypoglycemia)
  • How to recognize and treat high blood sugar (hyperglycemia)
  • Diabetes meal planning
  • How to give insulin
  • How to monitor blood glucose and urine ketones
  • How to adjust insulin and food intake during exercise
  • How to handle sick days
  • Where to buy diabetes supplies and how to store them

INSULIN

Insulin lowers blood sugar by allowing it to leave the bloodstream and enter cells. Everyone needs insulin. People with type 1 diabetes can't make their own insulin. They must take insulin every day.

Insulin is usually injected under the skin. In some cases, a pump delivers the insulin continuously. Insulin does not come in pill form.

Insulin preparations differ in how fast they start to work and how long they last. The health care professional will review your blood glucose levels to determine the appropriate type of insulin you should use. More than one type of insulin may be mixed together in an injection to achieve the best blood glucose control.

The injections are needed, in general, from one to four times a day. People are taught how to give insulin injections by their health care provider or a diabetes nurse educator. At first, a child's injections may be given by a parent or other adult. By age 14, most children can be expected (but should not be required) to give their own injections.

People with diabetes need to know how to adjust the amount of insulin they are taking in the following situations:

  • When they exercise
  • When they are sick
  • When they will be eating more or less food and calories
  • When they are traveling

DIET

People with type 1 diabetes should eat at about the same times each day and try to be consistent with the types of food they choose. This helps to prevent blood sugar from becoming extremely high or low. (See: Diabetes diet)

The American Diabetes Association and the American Dietetic Association have information for planning healthy, balanced meals. It can help to talk with a registered dietitian or nutrition counselor.

PHYSICAL ACTIVITY

Regular exercise helps control the amount of sugar in the blood. It also helps burn excess calories and fat to achieve a healthy weight.

Ask your health care provider before starting any exercise program. Those with type 1 diabetes must take special precautions before, during, and after intense physical activity or exercise.

  • Always check with your doctor before starting a new exercise program.
  • Ask your doctor or nurse if you have the right footwear.
  • Choose an enjoyable physical activity that is appropriate for your current fitness level.
  • Exercise every day and at the same time of day, if possible.
  • Monitor your blood glucose levels at home before and after exercising.
  • Carry food that contains a fast-acting carbohydrate in case your blood glucose levels get too low during or after exercise.
  • Wear a diabetes identification bracelet and carry a cell phone to use in case of emergency.
  • Drink extra fluids that do not contain sugar before, during, and after exercise.
  • As you change the intensity or duration of your exercise, you may need to modify your diet or medication to keep your blood glucose levels in an appropriate range.

SELF-TESTING

Self-testing refers to being able to check your blood sugar at home yourself. Regular self-testing of your blood sugar tells you and your health care provider how well your diet, exercise, and diabetes medications are working. This is also called self-monitoring of blood glucose, or SMBG.

A health care provider or diabetes educator will help set up a testing schedule for you at home.

  • Your doctor will help you set a goal for what level your blood sugar should be during the day.
  • The results can be used to adjust meals, activity, or medications to keep blood sugar levels within an appropriate range. Tests are usually done before meals and at bedtime. More frequent testing may be needed when you are sick, under stress, or adjusting your insulin dosing.

Testing will provide valuable information so the health care provider can suggest improvements to your care and treatment. Testing will identify high and low blood sugar levels before serious problems develop.

A device called a glucometer can provide a blood sugar reading. There are different types of devices. Usually, you prick your finger with a small needle called a lancet to get a tiny drop of blood. You place the blood on a test strip and put the strip into the device. You should have results within 30 - 45 seconds.

Keeping accurate records of your test results will help you and your health care provider plan how to best control your diabetes.

The American Diabetes Association recommends keeping blood sugar levels in a range that is based on your age. Discuss these goals with your physician and diabetes educator.

Before meals:

  • 70 - 130 mg/dL for adults
  • 100 - 180 mg/dL for children under age 6
  • 90 - 180 mg/dL for children 6 - 12 years old
  • 90 - 130 mg/dL for children 13-19 years old

At bedtime:

  • Less than 180 mg/dL for adults
  • 110 - 200 mg/dL for children under age 6
  • 100 - 180 mg/dL for children 6 - 12 years old
  • 90 - 150 mg/dL for children 13 - 19 years old

FOOT CARE

Diabetes causes damage to the blood vessels and nerves. This can reduce your ability to feel injury to or pressure on the foot. You may not notice a foot injury until severe infection develops. Diabetes can also damage blood vessels. Small sores or breaks in the skin may progress to deeper skin ulcers. Amputation of the affected limb may be needed when these skin ulcers do not improve or become larger or deeper.

To prevent problems with your feet, you should:

  • Stop smoking if you smoke.
  • Improve control of your blood sugar.
  • Get a foot exam by your health care provider at least twice a year and learn whether you have nerve damage.
  • Check and care for your feet EVERY DAY, especially if you already have known nerve or blood vessel damage or current foot problems.
  • Make sure you are wearing the right kind of shoes.

See: Diabetes foot care.

TREATING LOW BLOOD SUGAR

Hypoglycemia can develop quickly in people with diabetes. Symptoms typically appear when the blood sugar level falls below 70 mg/dL. If you have symptoms:

  • Do a blood sugar check.
  • If the level is low or you have symptoms of hypoglycemia, eat something with sugar: 4 ounces of fruit juice, 3 - 4 Lifesavers candies, or 4 ounces of regular soda. Overtreating a mild low blood sugar reaction can lead to problems with high blood sugar and difficult blood sugar control overall.
  • Symptoms should go away within 15 minutes. If the symptoms don't go away, repeat the sugar-containing food as above, and test the sugar level again. When your blood sugar is in a safer range (over 70 mg/dL), you may need to eat a snack with carbohydrates and protein, such as cheese and crackers or a glass of milk.

Ask your doctor if you need a glucagon injection kit to raise blood sugar quickly in an emergency.

MEDICATIONS TO PREVENT COMPLICATIONS

Your doctor may prescribe medications to reduce your chances of developing eye disease, kidney disease, and other conditions that are more common in people with diabetes.

An ACE inhibitor (or ARB) is often recommended as the first choice for those with high blood pressure and those with signs of kidney disease. ACE inhibitors include:

  • Benazepril (Lotensin)
  • Captopril (Capoten)
  • Enalapril (Vasotec)
  • Guinapril (Accupril)
  • Lisinopril (Prinivil, Zestril)
  • Perindopril (Aceon)
  • Ramipril (Altace)

Statin drugs are usually the first choice to treat an abnormal cholesterol level. Aim for an LDL cholesterol level of less than 100 mg/dL (less than 70 mg/dL in high-risk patients).

Aspirin to prevent heart disease is most often recommended for people with diabetes who:

  • Are older than 40
  • Have a personal or family history of heart problems
  • Have high blood pressure or high cholesterol
  • Smoke

TREATING HIGH KETONES

See: Diabetic ketoacidosis

Support Groups

For additional information and resources, see diabetes support group.

Expectations (prognosis)

Diabetes is a lifelong disease for which there is not yet a cure. However, the outcome for people with diabetes varies. Studies show that tight control of blood glucose can prevent or delay complications to the eyes, kidneys, nervous system, and heart in type 1 diabetes. However, complications may occur even in those with good diabetes control.

Complications

After many years, diabetes can lead to serious problems with your eyes, kidneys, nerves, heart, blood vessels, and other areas in your body.

If you have diabetes, your risk of a heart attack is the same as someone who has already had a heart attack. Both women and men with diabetes are at risk. You may not even have the typical signs of a heart attack.

In general, complications include:

Other complications include:

  • Erection problems
  • Infections of the skin, female genital tract, and urinary tract

Calling your health care provider

If you are newly diagnosed with type 1 diabetes, you should probably have medical follow-up weekly until you have good control of blood glucose. Your health care provider will review the results of home glucose monitoring and urine testing. The provider will also look at your diary of meals, snacks, and insulin injections.

As the disease becomes more stable, follow-up visits will be less often. Visiting your health care provider is very important for monitoring possible long-term complications from diabetes.

Call 911 if you have:

  • Chest pain or pressure, shortness of breath, or other signs of angina
  • Loss of consciousness
  • Seizures

Call your health care provider or go to the emergency room if you have these symptoms of ketoacidosis:

  • Confusion
  • Deep and rapid breathing
  • Extreme thirst and drinking and frequent urination
  • High glucose or ketone levels in your urine
  • Severe abdominal pain
  • Severe nausea and vomiting, and inability to drink liquids or eat
  • Shortness of breath
  • Sweet-smelling breath
  • Very high blood sugar

Also call your doctor if you have:

  • Blood sugar levels that are running higher than the goals you and your doctor have set
  • Numbness, tingling, pain in your feet or legs
  • Problems with your eyesight
  • Sores or infections on your feet
  • Symptoms that your blood sugar is getting too low (weakness or fatigue, trembling, sweating, feeling irritable, unclear thinking, fast heartbeat, double or blurry vision, uneasy feeling)
  • Symptoms that your blood sugar is going too high (being very thirsty, having blurry vision, having dry skin, feeling weak or tired, needing to urinate a lot)
  • You are having blood sugar readings below 70 mg/dL

You can treat early signs of hypoglycemia at home by eating sugar or candy or taking glucose tablets. If your signs of hypoglycemia continue or your blood glucose levels stay below 60 mg/dL, go to the emergency room.

Prevention

Currently, there is no way to prevent type 1 diabetes. There is no effective screening test for type 1 diabetes in people with no symptoms.

To prevent complications of diabetes, visit your health care provider or diabetes educator at least four times a year. Talk about any problems you are having.

Stay up-to-date with all of your vaccinations and get a flu shot every year in the fall.

References

Alemzadeh R, Wyatt DT. Diabetes Mellitus. In: Kliegman RM, ed. Kliegman: Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa: Saunders; 2007:chap 590.

American Diabetes Association. Diagnosis and classification of diabetes mellitus. Diabetes Care. 2010. 33 Suppl 1:S62-S69.

American Diabetes Association. Standards of medical care in diabetes -- 2010. Diabetes Care. 2010. 33 Suppl 1:S11-S61.

Eisenbarth GS, Polonsky KS, Buse JB. Type 1 diabetes mellitus. In: Kronenberg HM, Melmed S, Polonsky KS, Larsen PR. Kronenberg: Williams Textbook of Endocrinology. 11th ed. Philadelphia, Pa: Saunders Elsevier;2008:chap 31.


Review Date: 5/10/2010
Reviewed By: Ari S. Eckman, MD, Division of Endocrinology and Metabolism, Johns Hopkins School of Medicine, Baltimore, MD. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
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