Insulin is produced by specialized cells (beta cells) in the pancreas and is released into the bloodstream for the body to use. Insulin is required for glucose to enter the cells in the body to be used for energy. The pancreas of a person with type 1 diabetes produces little or no insulin, so the cells are unable to convert blood glucose into energy.

Symptoms of type 1 diabetes are caused when glucose blocked from entering the body's cells instead builds up in the blood. The symptoms usually develop quickly, over a few days or weeks. The patient may appear quite ill and complain of increased thirst, urination, and appetite as well as weight loss. If these symptoms are not treated quickly, a condition known as ketoacidosis can develop and lead to a dangerously high level of acid in the body -- the result of the body's inability to use glucose for energy.

Type 1 diabetes is relatively rare, accounting for around 1-2% of all people with diabetes. It usually is diagnosed in previously healthy children or young adults.

The insulin-producing cells in the pancreas are called beta cells. Once the beta cells have made the insulin, the pancreas releases the insulin into the bloodstream, which carries it to all the cells in the body.

Insulin is required for the entry of glucose into body cells. The insulin attaches to the cells, triggering a process that allows the glucose to enter them and be converted to energy.

The exact cause of type 1 diabetes is not known, but current medical research suggests that it results from an interaction between one's environment and inheritance (genetics). In people who are genetically more likely to acquire type 1 diabetes, it is believed that something in the environment, such as a viral infection, triggers the diabetes.

In a person with type 1 diabetes, the insulin-producing beta cells in the pancreas are "mistakenly" killed by an immune-system reaction resulting from exposure to a foreign substance -- such as a virus. Activation of the immune response sends millions of infection-fighting "T" cells, along with antibodies produced from the foreign-substance exposure, to "fight" and kill the beta cells. This process kills so many beta cells that the pancreas loses its ability to produce insulin.

Because little or no insulin is available to attach to body cells and allow glucose to enter, the amount of glucose circulating in the blood rises -- and keeps on rising.

Patients with diabetes -- whether type 1 or 2 -- have an increased risk of severe complications if the disease goes undiagnosed and untreated, or if it is poorly managed. The high blood glucose levels that occur in diabetes make it easier for blockages to form in the body's arteries. High blood glucose can also damage nerves in the body, causing numbness and tingling, especially in the legs and feet.

Diabetes-related damage to a person's circulation and nervous system increases the risk of heart attacks, strokes, blindness, kidney failure, and foot and leg amputations. These complications usually begin to occur approximately 10 years after the diagnosis of type 1 diabetes -- unless the person's blood glucose has been controlled. The good news is that aggressive treatment of diabetes can help keep these complications from developing.

Type 1 diabetes requires multiple daily insulin injections due to the inability of the pancreas to produce its own insulin. Also available is an insulin pump, worn on the body, that gives insulin directly and makes multiple daily shots unnecessary.

Structuring a proper diet -- also very important for effective diabetes treatment -- often requires close attention from a doctor and possibly a nutritionist to educate the patient regarding proper amounts of carbohydrates, protein, fats, and cholesterol. Besides eating the right foods, people with type 1 diabetes must time their meals to coincide with their insulin injections.

Regular exercise -- especially aerobic exercise -- can decrease the amount of insulin a person with type 1 diabetes needs and reduce the risk of diabetic complications. However, any change in activity must be discussed with the doctor to ensure that the person receives the proper amount of insulin.

Effective diabetes control and determination of the proper insulin dose depend on patients' regularly checking (monitoring) their blood glucose levels. Often done before each insulin injection, the test usually involves pricking a finger with a small needle, putting a drop of blood on a test strip, and inserting the strip into a machine (blood glucose monitor) that gives the glucose level within a few minutes. Checking blood glucose levels also helps to ensure that the patient's blood glucose level does not go too low -- which, if prolonged, can lead to mental confusion and coma.

People with diabetes also have blood drawn regularly in the doctor's office for various tests including one that is known as a HbA1C. This test gives the doctor an idea of how well the blood glucose has been controlled over the last several months.