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JAMA Patient Page
May 7, 2003


JAMA. 2003;289(17):2314. doi:10.1001/jama.289.17.2314

Insulin is produced by special cells in the pancreas, a large organ located behind the stomach. Insulin helps the body use or store glucose (sugar), which is produced during the digestion of food. Insulin is secreted into the blood at each meal and allows the body to use glucose as energy to fuel basic daily functions like moving and breathing. Insulin also enables the body to store extra glucose as fat. The May 7, 2003, issue of JAMA includes 2 articles about insulin therapy for patients with diabetes.


If there is not enough insulin or if the body cannot use the insulin produced, individuals develop a condition known as diabetes. Blood glucose levels can become high. If the body is unable to use glucose, it starts breaking down fats for energy. This produces waste products called ketones. High levels of ketones cause a dangerous condition called ketoacidocis that requires immediate medical attention. On the other hand, too much insulin can cause hypoglycemia (low blood sugar).

There are two major types of diabetes. In type 1 diabetes, the pancreas does not produce enough insulin. People with type 2 diabetes have what is called insulin resistance and eventually cannot make enough insulin to meet their needs. They may start treatment by losing weight with diet and exercise or by taking pills, or they may need insulin right away.


Insulin must be delivered to the bloodstream and is usually given by injection. Doctors or nurses teach patients how to inject insulin. Many individuals with diabetes inject insulin under the skin of the belly; others prefer the arm or thigh. Some patients with type 1 diabetes use an insulin "pump" that delivers insulin through a tiny tube placed under the skin.

Individuals with diabetes who need insulin must take it every day. They need insulin all the time to move glucose from the blood into the muscles where it is used, and they need enough insulin to absorb the glucose from food. The dose of insulin for meals depends on the amount of carbohydrates consumed. Blood glucose levels must be measured throughout the day by taking a small drop of blood (usually by a pinprick to the finger) and placing it in a meter that measures the blood glucose level.

There are several types of insulin that differ based on how long it takes the insulin to start working after it is injected (onset), when the insulin, is working hardest (peak), and how long the insulin lasts in the body (duration). Some individuals with diabetes use different types of insulin in various proportions and combinations depending on the time of day and timing of meals. Your doctor can help you determine the insulin types and schedule that are best for your needs.



To find this and previous JAMA Patient Pages, go to the Patient Page Index on JAMA's Web site at A Patient Page on diabetes was published in the September 26, 2001, issue, and one on diabetes management was published in the January 12, 2000, issue.

The JAMA Patient Page is a public service of JAMA. The information and recommendations appearing on this page are appropriate in most instances, but they are not a substitute for medical diagnosis. For specific information concerning your personal medical condition, JAMA suggests that you consult your physician. This page may be photocopied noncommercially by physicians and other health care professionals to share with patients. Any other print or online reproduction is subject to AMA approval. To purchase bulk reprints, call 718/946-7424.

Sources: American Diabetes Association, National Institute of Diabetes & Digestive & Kidney Diseases, American Association of Diabetes Educators