Friend with phlegmon in foot

#1

I’m sorry if this is off-topic - but a non-diabetic friend of mine (29 years old, male, otherwise fit, not overweight, etc) has phlegmon in his foot - it is the second time that he has had it - last year he needed several months to save his left foot.
Now it’s back, and he’s terrified - i’m just trying to understand what it is, and wondered if anyone here has struggled (and prevailed) with the same thing. When i researched it, it seemed to often occur in diabetics, so i thought maybe someone might know something…
I’m type one, and as yet, have no complications - like i said, i’m sorry if this is not the place for this kind of thing, but we are such a knowledgeable community… This friend has been very supportive of me getting used to my diabetes, and i would like to return the favour in whatever way i can…