Diabetes insipidus (DI) is a rare condition that occurs when the kidneys are unable to conserve water as they perform their function of filtering blood. It is often confused with diabetes mellitus because a symptom that both diseases have in common is frequent and excessive urination.

The word diabetes comes from the Greek word for siphon. A physician in ancient Greece coined the disease diabetes because sufferers passed water like a siphon.

The addition of insipidus and mellitus is to differentiate the concentration of the water passed by the person. Insipidus comes from the latin for no flavor. Urine passed by someone suffering from DI is highly diluted. Mellitus is also derived from the latin for honey and consequently diabetes mellitus (DM) is noted for passing urine that is sweet and concentrated.

There are four types of DI. These are :

Neurogenic diabetes insipidus - also called central diabetes insipidus.

This is caused when the anti-diuretic hormone or vasopressin produced by the hypothalamus and stored in the pituitary gland is not produced in sufficient quantity. Vasopressin causes the kidneys to preserve water but excrete the same amount of waste products.

Nephrogenic diabetes insipidus (NDI) also known as vasopressin resistance because the kidneys are unaffected by the secretion of vasopressin.

NDI is believed to by genetically passed on or caused by kidney diseases or as a side-effect of using drugs like lithium for other illnesses.

The third type is called gestagenic and occurs during pregnancy.

The fourth type is known as dipsogenic DI and is characterized by excessive fluid consumption. The excess fluids cause vasopressin to be supressed.

The primary symptoms of diabetes insipidus are excessive urination (polyuria) and excessive thirst (polydipsia). Symptoms for diabetes insipidus will be markedly abrupt. The sufferer will want to drink vast quantities of water. They will have difficulty sleeping as they will want to go to the toilet all the time. In the case of children there will be frequent bed wetting.

Diabetes insipidus testing involves a fluid deprivation test. As the name suggests the patient avoids drinking any fluids for a prescribed time period. The urine is then analyzed to determine it's concentration and composition.

Diabetes insipidus treatment involves having a good and plentiful source of fluid. In the case of neurogenic DI the drug desmopressin is taken to control the frequent thirst and urination.

There is no natural cure for diabetes insipidus but it doesn't pose any serious complications to the health if the person can take on fluids whenever they feel thirsty. It is confused with diabetes mellitus because the symptoms are similar but testing will determine which disease the person may be afflicted with.