Type 1 diabetes is a lifelong disease that develops when the pancreas stops producing insulin. Insulin lets blood sugar—also called glucose—enter your body's cells, where it is used for energy. Without insulin, the amount of sugar in the blood rises above a safe level, and the cells do not get the sugar they need. Over time, high blood sugar can damage blood vessels and nerves throughout your body and increase your risk of eye, heart, blood vessel, nerve, and kidney diseases. If your blood sugar level becomes very high, a life-threatening chemical imbalance (diabetic ketoacidosis) can develop.

Type 1 diabetes can develop at any age; however, it usually develops in children and young adults, which is why it used to be called juvenile diabetes. It has also been called insulin-dependent diabetes mellitus (IDDM) because insulin injections must be taken daily. One kind of type 1 diabetes—latent autoimmune diabetes of adulthood, or LADA—develops in adulthood. It sometimes is confused with type 2 diabetes because it starts later than most cases of type 1.

About 5% to 10% of all people with diabetes have type 1. 1 Type 2 diabetes is the most common type of diabetes; other forms of the disease include gestational and secondary diabetes.
What causes type 1 diabetes?

Insulin normally is made by beta cells in a portion of the pancreas called the islet tissue. For unknown reasons, type 1 diabetes develops because the body destroys the beta cells. This is called an autoimmune disease. (LADA develops in adulthood because it takes a long time for the body to destroy all the insulin-producing cells.)

Some people inherit a tendency for type 1 diabetes. People who have a parent, brother, or sister with type 1 diabetes are more likely than other people to develop the disease; however, most people with type 1 diabetes do not have a family history of it. Even with a family history of diabetes, you might not develop the disease unless you are exposed to something in the environment that triggers it. Experts debate whether enteroviral infections, especially Coxsackie B, and not being breast-fed beyond 3 months of age may increase the risk for type 1 diabetes.

Other factors that increase your risk are being white and having islet cell antibodies in your blood.

What are the symptoms?

Symptoms of diabetes are increased thirst, increased urination, weight loss, and sometimes increased appetite. These symptoms usually develop over a few days to weeks. Occasionally, some people notice symptoms after an illness, such as the flu. They may think the diabetes symptoms are related to the flu and not seek medical care early.

Sometimes, a person may develop symptoms of diabetic ketoacidosis before seeking medical care. Symptoms include:

    * Flushed, hot, dry skin.
    * Loss of appetite, abdominal pain, and vomiting.
    * A strong, fruity breath odor (similar to nail polish remover or acetone).
    * Fast and shallow breathing.
    * Restlessness, drowsiness, difficulty waking up, confusion, or coma.

How is it diagnosed?

A health professional diagnoses diabetes using a medical history, physical examination, and blood tests to measure glucose. The diagnosis needs to be confirmed by a blood glucose test done on another day. Some people are diagnosed with type 1 diabetes because they have diabetic ketoacidosis.