Adults who are skinny enough can wear Pampers diapers with some modification.
I have a 32 inch waist size and I have to modify the Pampers Baby Dry size 6 diapers to fit me somewhat.
I take the cloth covering off which make them smooth plastic and then take the Velcro Strip off the front and then cut it in half.
Then I glue one to each side of the diaper so that the tabs reach enough to attach to the diaper.
Then I stretch out the tabs as far as I can and then it fits some.
Then I run packing tape around the diaper waistband to keep the diaper on.
They still don't fit properly but they work good enough and are still fun.
Pampers for adults are just referred to as adult diapers or briefs.
Also depends is a diaper brand that is made for adults and they are in a away the old version of the plastic backed huggies diapers.
Depends protection with tabs is basically a plastic backed Huggies diaper that is plain white with tapes.
I wish they would make adult sized pampers diapers or adult sized Luvs diapers, Adult sized huggies diapers etc.
However you can buy thick adult baby diapers for adult babies such as from bambinodiapers.com or Abuniverse.
They do make some good diapers for adults who want baby prints and want diapers that resemble baby diapers.
There's much better diapers out there than the depends, or other cheaper adult diapers.
However if you cannot afford adult diapers and want diapers then even a size 6 or size 7 baby diaper is better than no diaper.
Even if you have to modify them a bit to make them fit somewhat.
Even though I mostly wear adult diapers I will sometimes modify Luvs size 6 diapers, Pampers Baby Dry size 6 diapers, Pampers Cruisers size 7 diapers or even other diapers such as Gentle Steps size 7 diapers to fit.
I then run some packing tape around the waist to make sure it stays up.
I mostly wear those for fun although I prefer adult diapers but sometimes I just want to wear and use an actual baby diaper even though it does not fit correctly.