I'm sure treating diabetes insipidus caused by a kidney disorder is more difficult. But treating diabetes insipidus caused by a lack of antidiuretic hormone (ADH) is not very difficult. The patient just has to replace the hormone in the body and the symptoms reduce. I think ADH is even available as a nasal spray. So it's easy to treat this condition if this is the cause.
My sister had a very mild version of this due to a throat infection. She was not given ADH. She was only told to drink more water which was enough in her case. Of course drinking more water is not the solution for more serious cases.