Airport Security: Would wearing a diaper through airport security present a problem?

Do you think you're the only one in this situation? It may be somewhat unusual at your age, but it's fairly common in older people. You will be by no means the first person the security people have seen in this situation. And they are not going to strip your clothes off right there at the scanner. If they have to investigate further, you will go somewhere more private.

Yea, plenty of adults wear diapers. They never just strip anyone in public. Chances are you will walk right through the scanner with no problem. In the unlikely scenario that you are selected for additional screening, you can request a private room.

If you're that concerned, go to the bathroom as soon as you get to the airport. Dump the diaper. Go through security and go to the bathroom and put another one on.
Then stand in the mirror, slap that padded @ss and say
"I have a nice butt"

There shouldn't be an issue. But if you're really concerned, then wait until after you've passed through security to go to the restroom and put on your diaper.

Don't be embarrassed. It will not be a problem. If the area should alarm on the body scanner, you will simply get a pat-down over the clothing. At no time will you be asked to remove any articles of clothing that will expose the diaper. (You can also request to have the pat-down be conducted in private and out of view of the public.)