Diabetes - Type 1

Alternative names
Insulin-dependent diabetes mellitus; Juvenile onset diabetes; Type 1 diabetes

Type 1 diabetes is a chronic (lifelong) disease that occurs when the pancreas produces too little insulin to regulate blood sugar levels appropriately.

Causes, incidence, and risk factors

Diabetes is a life-long disease for which there is not yet a cure. There are several forms of diabetes, including:

  • Type 1 diabetes, often called juvenile or insulin-dependent diabetes  
  • Type 2 diabetes, often called adult or non-insulin-dependent diabetes  
  • gestational diabetes, which occurs during pregnancy.

For all types of diabetes, the metabolism of carbohydrates (including sugars such as glucose), proteins, and fats is altered.

In type 1 diabetes, the beta cells of the pancreas produce little or no insulin, the hormone that allows glucose to enter body cells. Once glucose enters a cell, it is used as fuel.

Without adequate insulin, glucose builds up in the bloodstream instead of going into the cells. The body is unable to use this glucose for energy despite high levels in the bloodstream, leading to increased hunger. In addition, the high levels of glucose in the blood causes the patient to urinate more, which in turn causes excessive thirst. Within 5 to 10 years after diagnosis, the insulin-producing beta cells of the pancreas are completely destroyed, and no more insulin is produced.

Type 1 diabetes can occur at any age, but it usually starts in people younger than 30. Symptoms are usually severe and occur rapidly.

The exact cause of type 1 diabetes is not known. Type 1 diabetes accounts for 3% of all new cases of diabetes each year. There is 1 new case per every 7,000 children per year. New cases are less common among adults older than 20.


  • increased thirst  
  • increased urination  
  • weight loss despite increased appetite  
  • nausea  
  • Vomiting  
  • Abdominal pain  
  • fatigue  
  • absence of menstruation

Signs and tests
The following tests can be used to diagnose diabetes:

  • urinalysis shows glucose and ketone bodies in the urine, but a blood test is required for diagnosis  
  • fasting blood glucose is 126 mg/dL or higher  
  • random (nonfasting) blood glucose exceeds 200 mg/dL (this must be confimed with a fasting test)  
  • insulin test (low or undetectable level of insulin)  
  • C-peptide test (low or undetectable level of the protein C-peptide, a by-product of insulin production)


At diagnosis, the immediate goals of treatment are to treat diabetic ketoacidosis (also called DKA) and high blood glucose levels. Because of the sudden onset and severity of symptoms in type 1 diabetes, treatment for newly diagnosed people may involve hospitalization.

The long-term goals of treatment are to prolong life, reduce symptoms, and prevent diabetes-related Complications such as blindness, kidney failure, and amputation of limbs.

These goals are accomplished through education, insulin use, meal planning and weight control, exercise, foot care, and careful self-testing of blood glucose levels.


Insulin lowers blood sugar by allowing it to leave the blood stream and enter cells. Everyone needs insulin. People with type I diabetes can’t make their own insulin, and they must take insulin every day.

Insulin is injected under the skin using a syringe, or in some cases, an infusion pump delivers the insulin continuously. It is not available in an oral form.

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

The injections are needed, in general, from 1 to 4 times a day. People are taught how to give insulin injections by their health care provider or a diabetes nurse educator. Initially, 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.


Meal planning for type 1 diabetes requires consistency to allow food and insulin to work together to regulate blood glucose levels. If meals and insulin are out of balance, extreme variations in blood glucose can occur.

The American Diabetes Association and the American Dietetic Association has information for planning healthy, balanced meals. Consultation with a registered dietitian or nutrition counselor is an invaluable tool for meal planning and dietary control for diabetics.


Regular exercise is especially important for the person with diabetes, as it helps control the amount of sugar in the blood and helps burn excess calories and fat to achieve optimal weight.

Before people with diabetes begin any exercise program, they should obtain medical approval. Type 1 diabetics must take special precautions before, during and after participation in intense physical activity or exercise.


Blood glucose monitoring is done by checking the glucose content of a small drop of blood. The testing is done on a regular basis and will inform the person with diabetes how well diet, medication, and exercise are working together to control diabetes.

The results can be used to adjust meals, activity, or medications to keep blood-sugar levels within an appropriate range. It will provide valuable information for the health care provider to suggest changes to improve care and treatment. Testing will identify high and low blood-sugar levels before serious problems develop.


People with diabetes are prone to foot problems because of Complications related to the illness. Diabetes causes damage to the blood vessels and nerves, which can result in a decreased ability to sense trauma or pressure on the foot. A foot injury could go unnoticed until severe infection develops.

Additionally, diabetes alters the bodies immune system, decreasing the body’s ability to fight infection. Small infections can rapidly progress to death of the skin and other tissues, necessitating amputation of the affected limb.

To prevent injury to the feet, diabetics should adopt a daily foot care routine.


Low blood sugar, known as hypoglycemia, can occur in diabetics when they use too much insulin, exercise too much, or have not eaten enough food. Hypoglycemia can develop quickly in people with diabetes. Symptoms of low blood sugar typically appear when the sugar level falls below 70. Watch for weakness, shaking, sweating, headache, nervousness, and hunger.

If these symptoms occur and you have a blood sugar test kit available, do a blood sugar check. If the level is low, the person with diabetes should eat something with sugar: fruit juice, several teaspoons of sugar, a cup of skim milk, or regular soda. If you don’t have a test kit handy, sugar should be eaten anyway - it can’t hurt. Symptoms should subside within 15 minutes. If the symptoms don’t subside, more sugar should be eaten and the sugar level tested again.

AFTER the symptoms subside, more substantial food can be eaten. Eat simple sugar FIRST to get the situation under control. Even if you or your child is hungry, “real” food should not be eaten until the sugar level comes up - real food won’t produce enough sugar and takes too long to digest.

If you are a parent, relative, or friend of someone experiencing these symptoms, monitor the person closely. If symptoms become worse - confusion, seizures, or unconsciousness - give the person a shot of glucagon. If you don’t have glucagon, call 911 immediately.

You should have some glucagon stored for emergencies. Make sure everyone in your home, as well as babysitters and caregivers, knows how to use it. Periodically remind everyone how to use it, and check the expiration date.

Don’t panic. Glucagon works very fast - usually within 15 minutes. While you are waiting for the person to revive, keep him on his side to prevent choking. If the person is not better in 15 minutes, call 911.


When there is not enough insulin to move glucose into cells, glucose can build up in the blood. The body then looks for other forms of energy and uses fat as a fuel source. As fats are broken down, acids called ketones build up in the blood and urine. In high levels, ketones are poisonous to body tissue. This condition is known as ketoacidosis.

You can check for ketones using a simple urine test available at pharmacies. This test should be performed every 4-6 hours anytime a person with diabetes is registering blood sugar above 240; sick; unusually thirsty or has a dry mouth; urinating frequently; or vomited

The warning signs that ketoacidosis is getting serious might include flushed face, dry skin and mouth, nausea or vomiting, stomach pain, deep, rapid breathing, or fruity breath odor.

If these symptoms occur, call the doctor or go to the emergency room right away. If left untreated, this condition will lead to coma and even death.


  • Visit your physician and/or diabetes educator at least 4 times a year.  
  • Have your glycosylated hemoglobin (HbA1c) measured 2-4 times a year to evaluate your overall glucose control. (Ask your doctor how often you should be tested.)  
  • Have your cholesterol and triglyceride levels and kidney function evaluated yearly.  
  • Visit your ophthalmologist (preferably one that specializes in diabetic retinopathy) at least once a year, more frequently if signs of diabetic retinopathy develop.  
  • Every 6 months have a thorough dental cleaning and examination. Inform your dentist and hygienist that you have diabetes.  
  • Monitor your feet every day for early signs of injury or infection. Make sure your health care provider inspects your feet at each visit.  
  • Stay up-to-date with all of your vaccinations (including pneumococcal), and get a flu shot every year in the fall.


You are the most important person in managing your diabetes. Diabetes education is a crucial part of the treatment plan. Diabetes education basically involves learning how to live with your diabetes.

Knowledge of disease management is imperative to avoid developing short-term Complications such as hypoglycemia and hyperglycemia and to delay or slow the onset of long-term Complications of the disease such as diabetic retinopathy (eye disease) or nephropathy (kidney disease).

You should be knowledgeable about the basic principles of diabetes management. Basic “survival skills” include:

  • how to recognize and treat low blood sugar(Hypoglycemia)  
  • how to recognize and treat high blood sugar (hyperglycemia)  
  • diabetes meal planning  
  • how to administer insulin  
  • how to monitor blood glucose and urine ketones  
  • how to adjust insulin and/or food intake during exercise  
  • how to handle sick days  
  • where to buy diabetic supplies and how to store them

Support Groups

For additional information and resources, see diabetes support group.

Expectations (prognosis)

The outcome for people with diabetes varies. Recent studies show that tight control of blood glucose can prevent or delay the progression of eye disease, kidney disease and nervous system disease that is caused by diabetes. However, Complications may occur even when good diabetes control is achieved with insulin and diet.


EMERGENCY Complications:

  • Diabetic ketoacidosis     In a person with type 1 diabetes, the body will use fat as a fuel if insulin is not present. The by-products of fat metabolism are ketones. Ketones build up in the blood and “spill” over into the urine.     A condition called ketoacidosis develops when the blood is made acidic by the ketones.  
  • Hypoglycemia     Hypoglycemia (low blood glucose) occurs when the balance between insulin, food intake, and exercise is disturbed. Symptoms of mild hypoglycemia include hunger, nervousness, and fast heart rate. More serious hypoglycemia can lead to confusion and even loss of consciousness. Loss of consciousness due to low blood sugar is called hypoglycemic coma. LONG-TERM Complications: People who have had diabetes for several years are likely to develop long-term Complications, which can be minimized but not entirely eliminated by proper diabetic management:  
  • Vascular disease     By age 55, about 35% of men and women with type 1 diabetes have died from a heart attack compared to 8% of nondiabetic men and 4% of nondiabetic women.     People with type 1 diabetes are also at higher risk to develop blockages in the major arteries of the legs than nondiabetics. Lower the risk of vascular disease by aggressively treating cholesterol and blood pressure, exercising regularly, and avoiding or quitting tobacco products.  
  • MICROVASCULAR DISEASE     Microvascular (small vessel) changes occur in capillaries of every organ of the body. There is a thickening of the wall of the small blood vessels. These changes are responsible for many of the diabetes Complications.  
  • EYE Complications     Changes in the small blood vessels of the retina (also known as diabetic retinopathy) predispose the diabetic to several eye disorders. After 15 years of diabetes, 80% of diabetics will have some diabetic retinopathy.     If bleeding and scarring has developed, a retinal detachment may occur, causing blindness. Vascular changes in the iris may cause obstruction of the flow of ocular fluid and cause glaucoma. Diabetics are also more likely than nondiabetics to develop cataracts.  
  • Diabetic nephropathy (kidney disease)     Kidney abnormalities may be noted early in the disease. Poorly controlled diabetes may accelerate the development of kidney failure. Urinary tract infections in diabetics tend to be more severe and may result in kidney damage.     Diabetics are more vulnerable to kidney damage from high blood pressure than nondiabetics.  
  • Diabetic neuropathy (nerve damage)     People with diabetes may develop temporary or permanent damage to nerve tissue. Diabetic neuropathy is more likely to develop if blood glucose is poorly controlled. Some diabetics will not develop neuropathy, while others may develop this condition relatively early.     On average, symptoms such as numbness and tingling occur 10 to 20 years after diabetes has been diagnosed.  
  • DIABETIC FOOT PROBLEMS     The feet of people with diabetes are very susceptible to infection and injury. Many diabetes-related hospital admissions are for foot problems, and a significant number of non-accident-related leg amputations are performed on diabetics.     Several foot problems are common in people with diabetes, including skin changes (loss of hair; loss of ability to sweat; and dry, cracked skin), arterial insufficiency (impaired blood supply to feet), neuropathy, and specific foot deformities (hallux valgus, bunion, hammertoe, and calluses).  
  • SKIN AND MUCUS MEMBRANE PROBLEMS     People with diabetes are more likely than nondiabetics to develop infections. Hyperglycemia (high blood sugar) predisposes diabetics to fungal infections of the skin, nails, and female genital tract and to urinary tract infection.

Calling your health care provider

Medical follow-up for a person newly diagnosed with type 1 diabetes should probably occur weekly until good control of blood glucose is achieved. The health care provider will want to review results of home glucose monitoring and urine testing, and a diary of meals, snacks, and insulin injections.

As the disease becomes more stable, follow-up visits will be less frequent. Periodic evaluation is very important for the evaluation of long-term Complications associated with diabetes.

Call your health care provider or go to the emergency room if symptoms of ketoacidosis are present:

  • increased thirst and urination  
  • nausea  
  • deep and rapid breathing  
  • abdominal pain  
  • sweet-smelling breath  
  • loss of consciousness (This may occur in insulin dependent diabetics when a dose of insulin is missed, or if illness or infection is present.)

Go to the emergency room or call the local emergency number (such as 911) if symptoms of severe hypoglycemia or insulin reaction are present:

  • trembling  
  • weakness  
  • drowsiness  
  • headache  
  • confusion  
  • dizziness  
  • double vision  
  • lack of coordination  
  • convulsions or unconsciousness

Early signs of hypoglycemia may be treated at home by eating sugar or candy or injecting glucagon. If the signs of hypoglycemia are not relieved by the above action or if blood glucose levels remain below 60 mg/dL go to the emergency room.

Johns Hopkins patient information

Last revised: December 6, 2012
by Simon D. Mitin, M.D.

Medical Encyclopedia

  A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | 0-9

All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.