Yes, People with Diabetes Insipidus Drink Large Amounts of Water
Patients with diabetes insipidus (DI) do indeed drink loads of water—this is a compensatory response to massive urinary water losses, and free access to fluids is absolutely essential to prevent life-threatening hypernatremic dehydration. 1, 2
Why This Happens
The hallmark of DI is the excretion of large volumes of dilute urine (polyuria), which triggers an intense thirst response (polydipsia) as the body attempts to maintain fluid balance 3, 4. This creates a cycle where:
- Patients produce excessive dilute urine (often >3-4 liters per day in adults, with urine osmolality <200 mOsm/kg H₂O) 2, 5
- Compensatory polydipsia develops as the body's osmoreceptors detect rising serum osmolality and trigger thirst 1
- Water intake must match urinary losses to prevent dangerous hypernatremia 1, 2
Critical Importance of Free Fluid Access
All patients with DI must have unrestricted access to fluids at all times—this is not optional but life-saving. 1, 2 The guidelines are explicit:
- Patients capable of self-regulation should drink to thirst, as their osmosensors are more accurate than any medical calculation 1
- Most patients maintain normal serum sodium levels when they have free access to water 1
- Restricting fluid access can be fatal, leading to severe hypernatremic dehydration, seizures, coma, or death 2, 6
The Dangerous Exception: Adipsic DI
A critical caveat exists for patients who have lost their thirst mechanism (adipsia) due to hypothalamic damage affecting osmoreceptors 7. These patients:
- Cannot sense thirst despite severe dehydration 7
- Have significantly higher mortality rates (p=0.007) compared to non-adipsic DI patients 7
- Are at increased risk of serious infections requiring hospitalization (p<0.001) 7
- Require scheduled fluid intake rather than relying on thirst, with close monitoring of weight, fluid balance, and serum sodium 1
Special Populations Requiring Assistance
Infants and cognitively impaired patients cannot self-regulate fluid intake and require:
- Frequent offering of fluids beyond regular intake 1
- Close monitoring of weight, fluid balance, and biochemistry 1
- Intravenous 5% dextrose in water if fasting >4 hours (e.g., before anesthesia) 1, 8
Common Pitfall to Avoid
Never restrict fluids in DI patients unless they are receiving desmopressin treatment for central DI, where fluid restriction (1 hour before to 8 hours after dosing) is necessary to prevent hyponatremia 6. Even then, patients should drink to thirst outside these windows. The natural state of untreated DI requires massive fluid intake to survive.