diabetic foot ulcer

Kory 🎃
Does anyone have experience with this? I have a coworker who might be out for a while with a diabetic foot ulcer and none of us have any idea what this means. How do you know when it's serious enough to result in amputation or death? What are the stages and how long does something like this take to heal? I've googled it but am having a hard time getting a clear idea of severity and symptoms associated with the various levels. She's an older woman who doesn't monitor her diabetes and we're all concerned that she may have waited too long to get it checked out. Anyone ever deal with this?