I disagree with you. Telling the loader is usually a waste of time. They rarely will communicate with the screener. At best, the loader will then scream at the screener why you can’t take off your shoes. This may embarrass OP’s mom and is unnecessary to have such information screamed out to everyone in the security area.

The loader will probably just tell you to tell the screener anyway. It also is very likely that the screener won’t hear the loader because the screener is busy screening someone and besides with all the yelling that’s going on it’s hard to hear from that far away. The screeners usually ignore the loaders and are just focused on the stream of people going through the WTMD – it is unlikely that you will piss off the screener by telling them a legitimate reason for not taking off your shoes.

Saying you have a medical condition means everything, you don’t need a note. That is what the publicly stated policy says. That’s what the TSA screeners have been trained to listen for. If the screener doesn’t agree, ask to see a supervisor. They should not be subjected to a full secondary unless they alarm. Usually the screener should then yell, “female assist, no alarm, shoes” – just like in the old shoe carnival days. Regardless of what they say, when the secondary screener comes to help the OP’s mom, she should show her BP (showing no SSSS) to the secondary screener, tell him/her that she didn’t alarm and that she is diabetic and just needs her shoes screened. It usually is that easy.

What is not easy, and what is not right, is all of the accusatory yelling of lies that shoes “MUST” come off to people who should not have to take their shoes off. But of course, shoes shouldn’t be coming off of anyone, but that fact is irrelevant to the practical information that OP was looking for.