By Imagine feeling thirsty no matter how much you drink, and needing the toilet every hour, day and night. For people with diabetes insipidus, this can be daily life. Despite its name, the condition has nothing to do with blood sugar. It is a problem with the hormone that controls the body’s water balance: vasopressin.
This guide explains what diabetes insipidus is, why its name has recently changed, its symptoms and causes, how it is diagnosed, and how it is treated.
What Is Diabetes Insipidus?
Diabetes insipidus is a rare condition in which the kidneys cannot hold on to water properly. As a result, the body produces very large amounts of dilute urine, and people feel intensely thirsty to replace the lost fluid.
The cause lies with vasopressin (also called antidiuretic hormone or ADH). Normally, vasopressin tells the kidneys to reabsorb water. In diabetes insipidus, either there is not enough vasopressin, or the kidneys do not respond to it. Learn how the hormone works in what is vasopressin?
Why the Name Has Changed
The name “diabetes insipidus” has often caused confusion with diabetes mellitus (the common, blood-sugar type of diabetes). In 2022, international endocrinology and pituitary societies proposed new names that describe the actual problem:
| Old Name | New Name | What It Means |
|---|---|---|
| Central (cranial) diabetes insipidus | Arginine vasopressin deficiency (AVP-D) | The brain does not make or release enough vasopressin |
| Nephrogenic diabetes insipidus | Arginine vasopressin resistance (AVP-R) | The kidneys do not respond properly to vasopressin |
You may see both old and new names used by doctors and websites for some time. This article uses both so the information is easy to find.
Diabetes Insipidus vs Diabetes Mellitus
| Diabetes Insipidus (AVP-D / AVP-R) | Diabetes Mellitus (Type 1 / Type 2) | |
|---|---|---|
| Main problem | Water balance (vasopressin) | Blood sugar (insulin) |
| Blood sugar | Usually normal | High |
| Urine | Very large volume, very dilute | Can be increased, contains sugar when high |
| How common | Rare | Very common |
Both can cause thirst and frequent urination, which is why tests are needed to tell them apart. To understand blood sugar testing, read normal blood sugar levels.
Symptoms
- Passing very large amounts of urine (polyuria). In adults, more than about 3 litres a day is often used as a guide, and some people pass much more.
- Extreme thirst (polydipsia), often with a strong preference for cold water.
- Waking at night to urinate (nocturia), leading to poor sleep and tiredness.
- Pale, watery urine.
- Signs of dehydration if fluid is not replaced: dry mouth, dizziness, headache, confusion.
In babies and young children, signs can include unusual crying and irritability, wet nappies, poor feeding, fever, vomiting, and slow growth. Children with these symptoms need prompt medical attention.
Causes
AVP Deficiency (Central)
- Brain or pituitary surgery
- Head injury
- Tumours in or near the pituitary or hypothalamus
- Infections or inflammation affecting the brain
- Certain inherited genetic conditions
- No clear cause in some people (idiopathic)
AVP Resistance (Nephrogenic)
- Inherited genetic changes affecting the kidney’s response
- Certain medicines, most notably lithium, used for bipolar disorder
- High blood calcium or low blood potassium
- Chronic kidney disease or kidney damage
A Related Condition: Primary Polydipsia
Some people drink very large amounts of fluid for other reasons, such as habit or certain mental health conditions. This also leads to lots of dilute urine. Doctors must distinguish this from AVP deficiency, because the treatment is very different.
Diabetes insipidus can also appear temporarily during pregnancy, when the placenta produces an enzyme that breaks down vasopressin. This usually resolves after delivery.
How Is It Diagnosed?
Diagnosis is usually led by an endocrinologist and may include:
- 24-hour urine collection to measure total volume.
- Blood tests for sodium, osmolality, glucose, calcium, potassium, and kidney function.
- Urine osmolality to see how concentrated the urine is.
- Water deprivation test: fluids are stopped under careful supervision to see whether the kidneys can concentrate urine. A dose of desmopressin may then be given to tell central from nephrogenic causes.
- Copeptin testing: newer stimulation tests measuring copeptin, a marker released with vasopressin, are increasingly used in specialist centres.
- MRI scan of the brain and pituitary if AVP deficiency is suspected.
Never try to restrict fluids at home to “test” yourself. Water deprivation can be dangerous in people with this condition and must only be done in hospital.
Treatment
AVP Deficiency
The main treatment is desmopressin, a synthetic form of vasopressin. It comes as tablets, melts that dissolve under the tongue, nasal spray, or injection. Most people can live normal lives with treatment.
Desmopressin needs careful dosing. Taking too much, or drinking too much while on it, can cause low blood sodium (hyponatraemia), which can be serious. Doctors often advise drinking only when thirsty and may recommend a short daily break in the dose to let excess water clear. Read about the risks in low sodium (hyponatraemia) explained.
AVP Resistance
Desmopressin usually does not work well here. Treatment focuses on:
- Treating the underlying cause, such as correcting calcium or reviewing lithium with a specialist
- Drinking enough water to match losses
- A low-salt diet, and sometimes a low-protein diet, to reduce urine volume
- Certain medicines, such as thiazide diuretics, which paradoxically reduce urine volume in this condition
Never stop or change prescribed medicines without medical advice. See our medicines section.
Living With Diabetes Insipidus
- Always have access to water and toilets.
- Carry a medical alert card or bracelet, especially if you take desmopressin.
- Know the signs of both dehydration and low sodium.
- Plan ahead for illness, surgery, hot weather, and travel with your doctor.
- Attend regular blood tests to check sodium.
When to Seek Medical Help
See a doctor if you are passing large amounts of urine and are constantly thirsty. Seek urgent help if someone with known diabetes insipidus becomes confused, very drowsy, has a seizure, or cannot keep fluids down, or if a baby shows signs of dehydration.
Frequently Asked Questions
Is diabetes insipidus related to sugar?
No. It affects water balance, not blood sugar. The new names, AVP deficiency and AVP resistance, help avoid this confusion.
Can diabetes insipidus be cured?
It depends on the cause. Some forms are temporary, such as after some surgeries or in pregnancy. Many people with long-term AVP deficiency manage it well with desmopressin.
How much urine is too much?
For adults, regularly passing more than about 3 litres a day without drinking unusually large amounts is worth discussing with a doctor.
The Bottom Line
Diabetes insipidus, now called AVP deficiency or AVP resistance, is a rare condition where the body cannot hold on to water because of problems with vasopressin. It causes heavy urination and intense thirst. With proper testing and treatment, most people manage it well. Explore more in our hormones section.
Sources
- NHS: Diabetes insipidus
- The Pituitary Foundation
- You and Your Hormones, Society for Endocrinology
This article is for general education and is not medical advice. Always speak to a qualified healthcare professional about your health. Read our editorial policy.
