If wearing a diaper is a medical necessity, then it should be in your record as such. If you wear merely for the fetish of it, then best to keep that out of your official 'Files', unless you're willing to deal with any fallout that may happen down the road.
As someone who cannot be catheterized, I have zero choice but to wear a diaper, and I've got that in my medical file as well as what we used to call a 'R.E.D.' card (Record of Emergency Data), that I carry in my wallet. The last thing I want is to be MIS-treated should something dire happen and I am unable to speak for myself while undergoing emergency/any medical treatment.