Type 1 Diabetes Animated Guide

Definition

Diabetes is a disease that causes an abnormally high level of sugar, or glucose, to build up in the blood. Type 1 diabetes -- previously labeled insulin-dependent, or juvenile diabetes -- is caused by the destruction of cells in the pancreas (an organ located just behind the stomach) that produce the hormone insulin.

Symptoms

Symptoms of type 1 diabetes develop from a lack of insulin. Insulin allows glucose to enter the cells of the body and not build up in the blood stream. A person with untreated type 1 diabetes 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.

Lack of Insulin Production

Insulin is a hormone that is produced by specialized cells (beta cells) in the pancreas. The hormone is then released into the bloodstream where it is carried to all cells in the body. Insulin is required to allow glucose (sugar) to enter the cells in the body to be used for energy. The pancreas of a person with type 1 diabetes produces almost no insulin, so the cells of the body are unable to convert blood glucose into energy.

Who's at Risk?

Type 1 diabetes affects about 1% of the population and accounts for about 10% of all people with diabetes. It is usually diagnosed in previously healthy children or young adults. It is one of the most common childhood diseases. About one child or adolescent in 500 in the U.S. has type 1 diabetes. This type of diabetes occurs only about half as often in blacks and Asians as in whites.

Insulin Production in the Pancreas

The insulin-producing beta cells in the pancreas produce some insulin all the time in healthy individuals. Extra insulin is also released in response to a meal to normalize glucose levels.

Insulin Function 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.

Genetic, Environmental Causes

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.

Death of Beta Cells

In a person with type 1 diabetes, the insulin-producing beta cells in the pancreas are "mistakenly" killed by an immune-system reaction. This destruction of one's own body cells makes type 1 diabetes an example of an autoimmune disorder. 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 eventually loses its ability to produce insulin. The pancreas has great reserves of insulin, but once about 80% of the beta cells are destroyed, symptoms of type 1 diabetes develop.

Blood Glucose Rises

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

Damage to Circulatory and Nervous Systems

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

Damage to Circulatory and Nervous Systems

Damage to Specific Organs

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 type 1 diabetes can reduce the risk of developing these complications.

Insulin Injections

Type 1 diabetes requires multiple daily insulin injections to replace the inability of the pancreas to produce its own insulin. Insulin can not be given by mouth because stomach juices would make it inactive. Insulin can also be given by an insulin pump, which is worn on the body. A catheter placed under the skin allows insulin to be given continuously and in bursts before meals.

Healthy Diet

Structuring a proper diet is also very important for effective diabetes treatment. This 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

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 adjusts the dose of insulin appropriately.

Checking Glucose Levels

Effective diabetes control and determination of the proper insulin dose depend on patients regularly checking (monitoring) their blood glucose levels.

Often done before meals and at bedtime, 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 level does not go too low -- which, if prolonged, can lead to mental confusion and coma. Checking before driving a car and when sick or not eating is very important.

Another technology, continuous glucose monitoring, can be used to discover trends in glucose levels. It does not provide readings for individual tests and the device is not intended for long-term self-care.

HgA1C Monitoring

People with diabetes also have blood drawn regularly in the doctor's office for various tests including one that is known as a HgA1C. This test gives the doctor an idea of how well the blood glucose has been controlled over the last several months.

Symlin

Symlin is a synthetic version of a natural hormone that can regulate food intake amongst other actions. Patients taking Symlin often need reduced doses of insulin.

Research Continues

Prevention and effective treatment of diabetes are the subjects of ongoing and intensive medical research. As new discoveries are translated into useful therapies, products, and services, WebMD will incorporate these advances into its related programs.

If you or someone you love needs to know more about diabetes, please consult a physician. If you need to find a physician, try our Find a Physician Channel. For more information about diabetes, visit our Diabetes Health Center. Or sign up for the Diabetes Newsletter.

Diabetes Health Center

Illustrated Guide to Type 1 Diabetes