Hey, fellow barefooter here :).
I too had been told (and continue to be told by everyone who thinks they know better) that I couldn’t go barefoot because I had diabetes, but I never understood the reasons. About 10 years ago I met a guy who was a barefooter and he told me that wasn’t necessarily true and that he knew some other diabetic barefooters that were doing great, and in fact their foot health had improved. He connected me with the SBL (barefooters.org and the associated email group) which has all kinds of useful information, including some about diabetes. Also other group members with diabetes had advice.
Like other’s have mentioned, the problems come from poor control, which leads to poor circulation and/or neuropathy, which then leads to issues if you get a cut because you might not realize it and it could get infected and then due to the neuropathy and poor circulation the body can’t fight off the infection well and it may progress to amputation. That last bit being the only part of the story we ever seem to hear (if you get cut you will lose your foot!!!). The thing is, shoes aren’t always going to help. You can get foot injuries in shoes (blisters), and shoes are full of way more bacteria than the open air since they are the perfect breeding ground for fungus and bacteria (warm, damp, and dark), so say you get a blister or something from a shoe and your foot stays in that environment…that’s just going to compound the issue. Granted, unless someone has been going barefoot all the time on various surfaces and minimizing wearing anything (even those minimalist shoes) for a long time, they will likely have very soft and weak feet which will make the chance of injury greater, and if they can’t feel anything they will not have the feedback needed to adjust their step to avoid injury and such, so there may be no way around wearing shoes all the time. They would need to work on circulation and hopefully getting feeling back (which walking barefoot in a safe environment would help with), but that might not be possible.
Ditching shoes helps to improve the health of you feet and keep them healthy. Feet weren’t designed for shoes. Going barefoot, especially on more dynamic terrain like trails and such, strengthens your feet and improves circulation. When I started going barefoot everywhere 10 years ago, I never took that great of care of my diabetes, and hadn’t really since I was diagnosed. I still didn’t until about 3 years ago. Throughout that time I have had continual improvement in feeling, overall foot health (arches aren’t flat any more, and they are stronger overall), and circulation, both in my feet and lower legs. When I was in highschool I had a nerve test and they said I was starting to get nerve damage in my feet and legs. Well I just had a nerve test and a circulation test and had no signs of nerve damage and excellent circulation. For the first 3 years or so after I started doing it I was barefoot probably 95% of the time and there was a pretty dramatic positive change, but then for the last several years I had to start wearing boots/composite toe shoes for work for 8 hours a day which has unfortunately weakened them some. Thankfully in the office at work I can be barefoot, and outside of work I only wear shoes for specific circumstances where I truly need them, so I still have good circulation and feeling. Going barefoot also makes you more aware of your feet. I pay more attention to them now than I ever even thought of when I wore shoes all the time.
Bottom line, if you have good feeling and at least decent circulation, you are pretty much like everyone else without diabetes: Pay attention to what your feet are telling you, be mindful of your surroundings and the surfaces where you are or where you might go, train up to rougher surfaces, and don’t get too crazy as some environments just make shoes a necessity (chemicals, excessive heat, and unavoidable really sharp objects for instance). It sound like you endo isn’t harassing you so far so that is a good thing lol.