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This topic provides information about type 1 diabetes for adults and for parents of children who have been diagnosed with the disease in the past 6 weeks. If this topic doesn't answer your questions, one of the following topics may meet your needs.

• Type 1 Diabetes, if you want to learn about type 1 diabetes but do not have the disease.
• Type 1 Diabetes: Living With the Disease, if you or your adolescent has type 1 diabetes. If you have not read the topic, Type 1 Diabetes: Recently Diagnosed, you may want to read it first.
• Type 1 Diabetes: Children Living With the Disease, if your child age 11 or younger has type 1 diabetes. If you have not read the topic Type 1 Diabetes: Recently Diagnosed, you may want to read it first.
• Type 1 Diabetes: Living With Complications, if you have complications caused by your diabetes, such as eye, kidney, heart, nerve, or blood vessel disease.

What is type 1 diabetes?

Type 1 diabetes mellitus is a lifelong disease that develops when the pancreas can no longer produce insulin. Insulin lets sugar (glucose) enter your body's cells, where it is used for energy. Without insulin, sugar builds up in your blood. The level rises above what is safe for your body. Over time, high blood sugar levels can damage blood vessels and nerves throughout your body and increase your risk of eye, heart, blood vessel, nerve, and kidney disease.

Type 1 diabetes can develop at any age. But it usually develops in children and young adults. In the past, type 1 diabetes was called juvenile diabetes and insulin-dependent diabetes mellitus (IDDM).

What causes type 1 diabetes?

Insulin is made by certain cells (beta cells) in the pancreas. Type 1 diabetes develops because the body destroys the beta cells and therefore the pancreas's ability to produce insulin.

Some people inherit the risk for type 1 diabetes. But even these people may not develop type 1 diabetes unless other factors, such as exposure to certain viral infections, are present.¹

What are the symptoms of high blood sugar and low blood sugar?

The main symptoms of high blood sugar from diabetes are:

• Increased thirst.
• Increased urination.
• Weight loss.
• Fatigue.
• Increased appetite.

These symptoms usually develop over a few days to weeks. Some people have these symptoms before they are diagnosed, but they do not realize the symptoms are caused by diabetes. They may believe the symptoms are caused by the flu or some other illness.

When insulin levels drop very low, blood sugar can rise very high and a life-threatening situation called diabetic ketoacidosis (DKA) can develop. DKA is an emergency. Symptoms include:

• Flushed, hot, dry skin.
• A strong, fruity breath odor (similar to nail polish remover or acetone).
• Restlessness, drowsiness, or difficulty waking up. Young children may lack interest in their normal activities.
• Rapid, deep breathing.
• Loss of appetite, abdominal pain, and vomiting.
• Confusion.