Type 1 diabetes is an autoimmune disease. An autoimmune disease results when the body's system for fighting infection (the immune system) turns against a part of the body. In diabetes, the immune system attacks the insulin-producing beta cells in the pancreas and destroys them. The pancreas then produces little or no insulin. A person who has type 1 diabetes must take insulin daily to live.

At present, scientists do not know exactly what causes the body's immune system to attack the beta cells, but they believe that autoimmune, genetic, and environmental factors, possibly viruses, are involved. Type 1 diabetes accounts for about 5 to 10 percent of diagnosed diabetes in the United States. It develops most often in children and young adults, but can appear at any age.

Symptoms of type 1 diabetes usually develop over a short period, although beta cell destruction can begin years earlier. Symptoms include increased thirst and urination, constant hunger, weight loss, blurred vision, and extreme fatigue. If not diagnosed and treated with insulin, a person with type 1 diabetes can lapse into a life-threatening diabetic coma, also known as diabetic ketoacidosis.

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

Definition
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.

Symptoms

• 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)

Treatment
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.