fwiw, you could tell the screener you have diabetes with the best part of saying that is they can't ask you anything about it-period and end of story (but of course that is not being honest)

now, is there any legitimate reason that you need (n.b. need) to keep your shoes on (i.e. like me and my orthopedic shoes)? the reason i ask is back in february, i got to experience a new shoe/cast screening machine at jfk (mine was in the ua terminal). our very own LoganTSO provided me with a link ^ and you can see how i described what i did during the process. it does take a bit longer than the "shoe swab" but it is still better than having to take off my shoes.

so with all of that, you could always ask nicely if the checkpoint your are at has the "cast scope" machine