What is Diabetes Insipidus?
In contrast to diabetes mellitus, the disease known as diabetes insipidus has nothing to do with blood sugar or insulin. Even so, these two types of diabetes share some similarity in terms of symptoms. The most obvious similarity is that both diseases cause frequent and excessive urination, as well as increased thirst and increased need to urinate.
In addition to these symptoms, people with diabetes insipidus tend to feel intensely dehydrated if they do not drink frequent large amounts of water. The strong urge to urinate can cause night-time bedwetting, particularly in children. Young children with this disease tend to appear irritable and listless. They might be constipated, and have vomiting with an accompanying fever.
Children with diabetes insipidus are at risk of severe complications if not diagnosed. These include physical developmental delay, seizures, and intellectual development delay.
Diabetes Insipidus Causes
There are four different causes of diabetes insipidus. All of these causes are different from the cause of diabetes mellitus, which relates to the hormone insulin and to high blood sugar.
People with dipsogenic diabetes insipidus have excessive thirst. This causes them to drink large amounts of water, which results in the production of large amounts of urine.
Neurogenic forms of diabetes insipidus are caused by a deficiency in a hormone called vasopressin. This hormone controls urine output by acting as an anti-diuretic, which means the hormone causes the kidneys to excrete less water. Vasopressin is active when the body needs to conserve water by excreting smaller amounts of urine. When vasopressin is not produced in sufficient amounts, the kidneys produce much larger amounts of urine.
In nephrogenic diabetes insipidus the body produces sufficient quantities of vasopressin, but the kidneys are unable to respond to the hormone. This has a similar effect to neurogenic disease in that water excretion by the kidneys is not able to be limited by the action of vasopressin.
Women who are pregnant can develop gestagenic diabetes insipidus. This form of the disease results from a temporary vasopressin deficiency. In most cases the disease resolves spontaneously when the pregnancy ends.
Treatment for Diabetes Insipidus
People with the neurogenic or gestagenic forms of the disease can be treated with supplemental vasopressin; however dipsogenic and nephrogenic diabetes insipidus are not always treatable. In many cases people with these forms of diabetes insipidus do not require treatment, as the condition is rarely life-threatening.
People with diabetes insipidus are at risk of severe dehydration, however, and must drink large amounts of water to replace what is excreted by the kidneys. In addition they must generally avoid or limit activities which promote water loss via sweating or other means. For example, heat exposure and sports participation must often be limited.
One of the main risks for people with this disease is gastrointestinal illnesses that cause diarrhea. This is a risk because diarrheal illnesses increase the rate of water excretion, and can increase the risk of dehydration. Sometimes hospital care can be needed to ensure that dangerous levels of dehydration do not occur.
James CM Chan, MD, for eMedicine: Diabetes Insipidus
National Institute of Health Kidney and Urologic Diseases Information: Diabetes Insipidus
National Institute of Health MedlinePlus: Diabetes Insipidus