I had an interesting experience with this YEARS AGO. We're talking, back when I was 23 or so. No internet, no adult incontinence products as there are today. I still lived with my parents so, no way I could have cloth diapers even if I'd known where to find them and been able to afford them because I'd have had to keep them for days in a bag in the closet, sneak them out of the house and off to a laundromat to wash them / back again.
I'd often buy toddler-sized Pampers in the purple boxes and tape two of them together lengthwise and wear because I could easily sneak those out a few at a time and toss them in a dumpster somewhere. But at some point I became aware that yes, there were "adult-sized" diapers but they were the kind they used at hospitals and could only be bought from a health care supply place.
So off I went to one of these places--where you go for crutches, wheelchairs, all those sorts of things. This friendly young guy about my age came out and asked what I needed and I asked about this and yes, they did have them. You could only buy them by the case and they were called "Disposable Adult Diapers". I asked how much a case was and he told me and I handed him the money.
Then he started asking questions. Good natured, of course. Stuff like "Why are you paying for them, your insurance would cover this!" Well at the time I only worked part-time and didn't have my own policy and was on my parents' policy. Even if I'd had my own I'm sure I'd have had to be diagnosed with incontinence in order for insurance to cover them. So that wasn't an option so I blurted out "Oh they're not for me they're for my brother."
He then kept asking questions. "Who is your brother? Does he have insurance?" He was trying to save me money but I just wanted to pay him and leave and eventually I said "Can I just please pay you for these?" He said "Well..... whatever...." and I did, grabbed them, and left.
That was a very nerve-wracking, embarrassing experience. Afterward I thought "Well maybe I should have just told him the truth--there's nothing wrong with me, I just LOVE WEARING DIAPERS!"
Worst part of this was, they WERE NOT good diapers. Large, rectangle-shaped and thin. After buying them and trying one of them I never wore the others, instead I just used them for pads to put underneath my taped-together Pampers.