I'd highly recommend making sure you change if wet before going through security and maybe reduce your fluid intake within the hours before (at least in terms of caffeinated beverages, etc.) to stay dry. Just keep in mind that security personnel are well-trained and have probably come across people with these issues before, and when it comes down to it you probably won't see them ever again and it is their job to keep things discrete. If you do get an awkward run-in for some reason they'd probably be just as embarrassed as you about it and wouldn't bother you about it. I'd definitely recommend against trying to make it through without a diaper on if you need them as a leak would be so much worse to deal with