DH is diabetic and on the pump. He did set off the metal detector several times before TSA figured out that the belt clip for his pump holster was setting off the alarms (and they couldn't ask him to remove it, since they thought it was part of the pump itself - DH voluntarily took off the holster, sent it through the x-ray machine, and carried the pump through the detector), but that's been it so far...
I second getting the note from the MD...