Hi what kind of doctor diagnoses and treats diabetes insipidis? nephrologist? endocrinologist?

Both: Both can diagnose and treat this condition.

One or other: Depending on their experience.

Diab Insipidis: Both nephrologist and endocrinologist can diagnose and treat this condition. There are two forms of DI. One is a pituitary deficiency of vasopressin. The second is kidney hyporesponse to vasopressin. Both are usually treated with exogenous vasopressin, though using HCTZ (hydrochlorothiazide) with low salt diet can also be used. Testing involves water deprivation testing - avoiding any fluid x 12 hours with urine test