My brother has diabetes type II. Recently his toes turn black. The doctor said he need to remove the toes. What happen if he refuse to remove the toes and give up treatment
We can't give medical advice as such.... But, ah...
If the toes are black due to necrosis, they're dead. They're not going to turn a healthy pink ever again. There'd be no bloodflow to them anymore, and they will eventually start to decay. Which could then rather swiftly lead to sepsis/gangrene (blood poisoning), and death. If they're indeed gone, they're gone, and there's no saving them.
Personally, if my toes were that far beyond help, I'd have them removed with haste, because what's a few toes in the grand scheme of things...? My uncle lost both his legs, just above the knee. And he was still counting himself lucky, because he was alive to tell the tale. (Which he delighted in doing, as gruesomely as possible!).
It's your brother's choice, of course, but trust the docs on this one. If they say they need to go, they do, really, really, really, need to go. It's a life-and-death kind of thing, not a cosmetic matter.
Good luck, and all the best to your brother!
Jo