My father was diabetic and had an amputation following a crush injury to his ankle.
He faced a lengthy recovery period, bone grafts, metal plates, a fused ankle and, having been diabetic and without good BG control for some 15 years at that point and already experiencing circulation problems, no guarantee that any of it would work at all.
He chose amputation, and after a relatively short period of healing and getting used to using a prosthesis, he got on with his life. Would he have rather had his own foot, I'm sure of it, but after the amputation he had a better quality than he would have had if he'd gone through all the trouble to try to keep it. It was a very personal decision and I think he chose well, all things considered.
There were some things he couldn't do as well with only one real foot, but he found ways to do all the things he loved and had an active life. If were in his position, I believe I would have made the same choice.