Diabetes insipidus 

Introduction 

Different types of diabetes

It is important not to confuse diabetes insipidus with diabetes mellitus, which most people just know as ‘diabetes’. There are two types of diabetes mellitus: type 1 diabetes and type 2 diabetes.

Diabetes mellitus is far more common and occurs when there is too much glucose (sugar) in the blood.

The word ‘diabetes’ relates to the Greek verb for urination. It is used to refer to both diabetes insipidus and diabetes mellitus as they affect the chemical make-up of urine (although the treatments for each condition are very different).

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Diabetes insipidus is a rare disorder where the system used by the body to regulate its water levels becomes disrupted.

This disruption leads to the main symptoms of diabetes insipidus:

  • excessive and prolonged thirst
  • needing to urinate frequently
  • passing large amounts of urine – in the most severe cases a person can pass up to 20 litres a day

Read more about the symptoms of diabetes insipidus.

What causes diabetes insipidus?

Diabetes insipidus is caused by problems with a hormone called antidiuretic hormone (ADH), also known as vasopressin.

ADH plays a key role in regulating the amount of liquid in the body.

ADH is made by a part of the brain called the hypothalamus and is stored just below the brain, in the pituitary gland, until needed.

When the amount of water in the body becomes too low, ADH is released from the pituitary gland. This helps to retain water in the body by stopping the kidneys producing urine.

In cases of diabetes insipidus, ADH does not stop the kidneys from producing urine and allows too much water to be passed from the body.

Read more about the causes of diabetes insipidus.

Types of diabetes insipidus

There are two main types of diabetes insipidus:

Cranial diabetes insipidus

Cranial diabetes insipidus occurs when there is not enough ADH in the body to regulate the production of urine.

This is the most common type of diabetes insipidus and can be caused by damage to the hypothalamus or pituitary gland, for example after an infection, operation, brain tumour or head injury.

However, in around one in three cases of cranial diabetes insipidus there is no obvious reason why the hypothalamus stops making enough ADH.

Nephrogenic diabetes insipidus

Nephrogenic diabetes insipidus occurs when there is enough ADH in the body, but the kidneys fail to respond to it. It can be caused by kidney damage.

Some medications, especially lithium (used in the treatment of a number of serious mental health conditions, such as bipolar disorder), have been known to cause nephrogenic diabetes insipidus.

Very rarely the genes a person inherits can trigger nephrogenic diabetes insipidus.

Treating diabetes insipidus

In mild cases of cranial diabetes insipidus treatment may not be required as long as a person compensates for excessive urination by drinking more water.

However, a medication called desmopressin can be used to replicate the functions of ADH if necessary.

Nephrogenic diabetes insipidus is often treated with medications called thiazide diuretics which reduce the amount of urine the kidneys produce.

Read more about the treating diabetes insipidus.

Complications

The levels of fluids inside the body could potentially drop to a dangerously low level, which is known as dehydration.

Mild dehydration can be treated with rehydration solutions which replace fluid, as well as lost minerals, salts and sugars. Severe dehydration is treated in hospital.

Read more about the complications of diabetes insipidus.

Who is affected

Diabetes insipidus is a rare condition, affecting an estimated 1 in 25,000 people. As the condition is usually acquired through injury or infection, it can affect people of all ages and ethnic backgrounds. Both sexes are equally affected.




Page last reviewed: 01/05/2012

Next review due: 01/05/2014

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Thirst

Feeling thirsty all the time and for no obvious reason is not normal and should be investigated by your GP