What is diabetes insipidus?

Have you ever heard of diabetes insipidus and wondered what it was?  Here is a little more information to avoid confusion about the terms we use to describe diabetes.  Though diabetes insipidus shares the same "first name" with type 1 diabetes mellitus and type 2 diabetes mellitus, it is not related to the other two. Both type 1 and type 2 diabetes mellitus have been called “sugar diabetes” because they involve insulin and the control of blood sugar. In type 1 diabetes mellitus (which used to be called juvenile diabetes), there is destruction of the insulin-producing cells of the pancreas, which leads to decreased production of insulin and abnormal handling of sugar by the body. In type 2 diabetes, (formerly called adult-onset diabetes), there is an abnormally high “resistance” to the effects of the insulin, which leads to high blood sugars.

Diabetes insipidus (DI) has nothing to do with insulin or blood sugar. It is a rare disorder caused by a decrease in secretion of a hormone called antidiuretic hormone (ADH), or an abnormally high resistance to the effects of the ADH hormone on the kidney. Without normal levels of ADH, the kidneys cannot properly control how much water is retained in the body and how much is lost in the urine. People with DI urinate very often and the urine is very dilute. They are also very thirsty, and can become dehydrated easily. (These are also symptoms of type 1 and type 2 diabetes.) 

There are many causes of DI including damage to the pituitary gland in the brain, head injuries, cancers, eating disorders, and psychiatric disorders. In about 30% of cases, however, no cause can be found.

Treatment depends in part on the cause of the diabetes insipidus. Sometimes people with DI can be treated with liquid solutions, either drinking them or getting them intravenously, to replace lost fluids and avoid dehydration. Medication, including a synthetic version of the ADH hormone known as DDAVP, may be required. One type of DI does not respond to synthetic hormone, and medications such as hydrochlorothiazide (HCTZ) or Moduretic are used instead. It is important that all people with diabetes insipidus wear a medical-alert bracelet or carry a wallet card to help make sure they are always given proper treatment.

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Julie K. Silver, M.D., is an assistant professor in the Department of Physical Medicine and Rehabilitation at Harvard Medical School. She is also the Chief Editor of Books for Harvard Health Publications.

Nearly 21 million Americans suffer from diabetes, and as anyone who has been affected by the disorder knows, it is about much more than a statistic: it means a new way of life. Diabetes: A plan for living is a special report from Harvard Medical School that will help you learn how to better understand and manage your diabetes, including type 1 and type 2, as well as other variations of the disease. This report will show you that it’s not just possible to live with diabetes; it’s possible to live well.

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