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Type 1 Diabetes

What Is Type 1 Diabetes?

Type 1 diabetes is a chronic disease. In type 1 diabetes, the cells in the pancreas that make insulin are destroyed, and the body is unable to make insulin. While the exact cause of type 1 diabetes is unknown, it is thought to be an autoimmune response; something, such as a virus, triggers the body’s immune system to create an antibody that kills the cells in the pancreas responsible for making insulin.

Insulin is a hormone that helps to lower blood sugar by allowing sugar to pass from the blood into the cells. When there is no insulin, blood sugar, called glucose, builds up in the blood. Glucose is a natural sugar that your body uses as a source of energy. It is obtained from food. Extra glucose is stored in the liver and muscle tissues. It is released when extra energy is needed, such as between meals or when sleeping. Normal levels of blood sugar are helpful, but when it builds up, it can cause both short term and long term problems.

What Causes Type 1 Diabetes?

Type 1 diabetes is an autoimmune disease. It occurs when the body’s immune system attacks the beta cells of the pancreas. These are the cells that create insulin. People with type 1 diabetes cannot make enough insulin to control their blood sugar.

The reasons why the immune system attacks beta cells are unknown.

Who Is at Risk for Type 1 Diabetes?

Risk factors for type 1 diabetes are poorly understood. However, some factors have been tentatively identified.

Heredity may be important in some cases of type 1 diabetes. If you have a family member with the condition, your risk of developing it is increased. Several genes have been tentatively linked to this condition. However, not everyone who is at risk for type 1 diabetes develops the condition. It is believed that there must be some type of trigger that causes type 1 diabetes to develop.

Younger people are more likely to be diagnosed with type 1 diabetes. The most common age of diagnosis is between 11 and 14 years old. It is rarely diagnosed after age 40.

Cold weather may increase risk for type 1 diabetes, so those who live in cold climates may have a higher risk. People in Finland are approximately 300 times more likely to develop type 1 diabetes than those in the United States.

People with certain antibodies may also have a higher risk of developing type 1 diabetes.  These antibodies, which are made by the body in response to certain viruses, are found in some people years before the diagnosis of type 1 diabetes. It is also thought that viruses may play a role in developing diabetes.

Race may be a risk factor for type 1 diabetes. It is more common in Caucasians than in those of Asian and African descent.

Finally, early diet may play a role, since those who are breastfed and introduced to solids foods later show a lower risk of type 1 diabetes.

What Are the Symptoms of Type 1 Diabetes?

Type 1 diabetes usually develops more quickly than type 2 diabetes, which can take years. The following symptoms may be signs of type 1 diabetes:

  • hunger
  • thirst
  • blurry vision
  • fatigue
  • excessive urination
  • dramatic weight loss in a short period of time
  • numbness or lack of sensation in the feet
  • Ssymptoms of ketoacidosis (rapid breathing, dry skin and mouth, flushed face, fruity breath odor, nausea, vomiting or stomach pain)

If you have one or more of these symptoms, you should visit your doctor.

How Is Type 1 Diabetes Diagnosed?

Type 1 diabetes is usually diagnosed through a series of tests. Because type 1 diabetes often develops quickly, people are diagnosed when they have signs and symptoms of high blood sugar and their blood glucose level is over 200 mg/dL.

A fasting blood test can be used to diagnose type 1 diabetes.

In this test, you fast overnight before having your blood sugar tested. It is more reliable than a random test. A value of less than 100 mg/dL is considered normal. A value of 100 mg/dL to 125 mg/dL indicates pre-diabetes. Someone with a value of 126 mg/dL or a higher is diagnostic for diabetes.

How Is Type 1 Diabetes Treated?

Because the body no longer makes insulin, people with type 1 diabetes will need to take insulin and manage their diet and exercise to keep blood sugars within a healthy range.


People with type 1 diabetes must take insulin everyday. The insulin is usually administered by injection. However, some people use an insulin pump. The pump injects insulin through a port in their skin. It can be easier for some people than sticking themselves with a needle. It may also level out blood sugar highs and lows.

Insulin needs vary throughout the day. People with type 1 diabetes regularly measure their blood sugar to figure out how much insulin they need. Both diet and exercise can affect blood sugar levels.

Diet and Exercise

People with type 1 diabetes should eat regular meals and snacks to keep blood sugar stable. A dietitian familiar with diabetes can help to establish a healthy, balanced eating plan. Exercise also affects blood sugar and insulin amounts may need to be adjusted to account for this.

Foot Care

Type 1 diabetes can damage the nerves, especially in the feet. Small cuts can quickly turn into severe ulcers and infections. Therefore, diabetes treatment should include regular foot checks. Injuries should be brought to the attention of a doctor.

What Are Complications of Type 1 Diabetes?

High blood sugar levels can cause damage to various parts of the body. Poorly managed diabetes increases the risk of these complications, which include:

  • increased heart attack risk
  • eye problems, including blindness
  • nerve pain
  • infections on the skin, especially the feet, that could require amputation in serious cases
  • kidney damage
  • high blood pressure
  • high cholesterol

What is the Prognosis for Type 1 Diabetes?

Type 1 diabetes can be managed with proper treatment. People who manage their diabetes can live a healthy life.

Content licensed from:

Written by: Rose Kivi and Elizabeth Boskey, PhD
Medically reviewed on: May 20, 2014: Peggy Pletcher, MS, RD, LD, CDE

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
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