09/09/2025
From my inbox...
....✍️
Doc, I drink water like a fish but still feel thirsty. And I’m always running to the toilet!"
This is something you might hear from someone living with Diabetes Insipidus a condition that’s often misunderstood, even by those in health circles.
What Is Diabetes Insipidus?
Diabetes Insipidus (DI) is a rare condition where the body loses too much water through urine, leading to constant thirst and frequent urination. It has nothing to do with sugar, unlike Diabetes Mellitus.
The word “Diabetes” simply means "to pass through" referring to urine flow, and "Insipidus" means tasteless because the urine in DI is dilute and watery.
What People Often Think but Isn't True
Some think it's caused by high blood sugar. But that’s not the case. DI has nothing to do with blood glucose. Others confuse it with being a psychological condition from drinking too much water. That may happen in a rare case called primary polydipsia, but that’s not true DI.
The Real Causes
Diabetes Insipidus is caused by a problem in either,
THE BRAIN, where a hormone called ADH (antidiuretic hormone) is made. If the brain doesn’t produce or release enough ADH, that’s called Central Diabetes Insipidus
THE KIDNEYS, where ADH acts. If the kidneys don’t respond to ADH, even when it's present, that's Nephrogenic Diabetes Insipidus
Sometimes it's caused by head injury, brain surgery, tumors, infections, or certain medications like lithium.
How It Develops in the Body
Normally, ADH helps your kidneys retain water when you are dehydrated or haven’t drunk much. It signals them to concentrate urine and send water back into the blood.
But in DI, there's either,
Too little ADH (Central DI), or
No kidney response to ADH (Nephrogenic DI)
So, the kidneys let too much water go. The body loses water rapidly through dilute urine. This makes the person very thirsty, trying to replace what’s lost.
Symptoms and Signs You will notice
Excessive urination (polyuria), urine is pale and watery
Excessive thirst (polydipsia), especially craving for cold water
Waking up at night to urinate
In children they may wet the bed or show poor growth
In severe cases dehydration, low blood pressure, dry mouth, and confusion
These symptoms come because the body is trying to balance water loss by pushing you to drink more, but still keeps losing it.
Why These Symptoms Appear
The excessive urination is due to the kidneys losing water without control.
Excessive thirst is the brain’s way of trying to restore the lost fluids.
If a person doesn’t drink enough to replace the water, they may become dehydrated quickly leading to dry skin, fatigue, dizziness, or even confusion.
Treatment
Central DI treated with Desmopressin (DDAVP), a synthetic version of ADH
Nephrogenic DI treated by:
Low salt diet
Thiazide diuretics (ironically, they reduce urine by affecting kidney handling of salt and water)
Sometimes NSAIDs like indomethacin
Encourage good water intake to avoid dehydration.
How To Prevent Complications
You can’t always prevent DI especially if it’s due to genetics or brain trauma but you can:
Recognize symptoms early, avoid medications that cause it if possible (like lithium).
Follow treatment to keep water balance normal. Educate caregivers for children with DI
If someone is drinking tons of water and urinating nonstop, don't just assume it’s “sugar” (Diabetes Mellitus). It could be something else entirely like Diabetes Insipidus.
