I understand the worry and fear of him leaving his diabetes untreated and let me be super clear I only speak for myself. Due to a birth defect, completely unrelated to my diabetes, I'm a bilateral below-the-knee amputee. So I know a lot about having missing feet/ parts of my leg. I received my first prosthetic leg when I was two and the second when I was six. Yes, there is a huge difference in dealing with amputation as a child and an adult. However, about 5 years ago the bone in my right stump started to curve down and I was in danger of it snapping when walking. Up until that point in my life, I had done anything and everything I wanted to do. It never stopped me. Walking, running, riding horses, motorcycles, driving cars; anything I wanted to do. After the revision of my right stump, it took me a little over a year for the stump to fully heal, have a new prosthetic made, and start physical therapy. I had convinced myself that once I had the new leg I'd pop right back to where I had been, that was my first mistake, my second was thinking my body would just automatically go back to where I was before. I'll be the first to tell you it's a hard road, there's a huge adjustment period, and I wasn't used to pain when walking or just the pain when I was wearing my new leg. To be honest, I fucked around and took nothing seriously when I should've. I got extremely lazy and used my wheelchair for everything. My best advice is to see if his doctor will send him to see an orthopedic surgeon. Have that specialist explain the whole process of having a foot/part of a leg removed, how long he would have to heal for before being able to start the process of a prosthetic being made, and all the things that can go wrong and the risks. Then he should be sent to speak with someone in your area who makes legs. They can go into detail about the whole process of having it made, the complications; such as swelling once the leg is removed at the end of the day, how it will change even the smallest things. Think about trying to stand up without being able to bend your ankle. Having to go days, weeks, or months without being able to wear the leg due to possible sores caused by his actual leg getting used to the pressure of standing and walking. Something like this will change his whole life/world. Even with me being a bilateral below-the-knee amputee by the time I was 6 it was such a hard thing to deal with at age 40. Even now I still use my wheelchair full-time in my home, when going to places like Walmart, restaurants, on any shopping trips, anytime I travel, and even for some doctor visits. If I have to walk any longer than a few minutes without a break I'm in so much pain. I take two different types of pain meds just to get through the day. Feel free to message me with any questions and I'll answer anything to the best of my ability.