"Someone on this site wrote that Medicare will cover a DEXA once a year if you are on osteoporosis medication"

That was me, and it's that Medicare will cover *more* than one DEXA a year if you're on osteoporosis medication. Even the facility I went to double-checked it, because at first the technician said "you were last here just under a year ago, this isn't covered." Then she checked with the staff who confirmed that it's covered because I've been on meds.