The question is quite simple and mostly applies to those among us who wear their diapers in public, or wear them at home under clothes.
Do you wear underwear over your diaper? Yes? No? Do you have special underwear for that (i.e. snug underwear to keep the diapers in place), or do you wear your normal everyday underwear over your diapers?
As for me, I always wear my normal every-day underwear over my diaper when I'm wearing pants with my diaper for three reasons:
(1) To keep the diaper in place and thus reduce the bulge and noise of the diaper.
(2) To soak up small leaks before they reach the outside pants and become visible to the public. It happens quite often that there's a small wet patch on the underwear when I finally take off the diaper.
(3) To avoid having to go commando when I have to take off my diaper before I get back home and can put on underwear. If my diaper becomes too wet, I can just take it off, pull down underwear and pants and continue my day in my normal clothes.