I have diebetes insipidus - random diagnosed at 22- just had first child at 26 and don't need my meds now? why?

I don't know: Pregnancy and the high levels of hormones can induce many changes- most beneficial and some not. I hope in your case that something happened to correct the "random" dysfunction that cause the diabetes insipidus earlier. Lucky you. It is also possible that months from now as your body returns to pr-epregnat state that it may reappear.