My comments would be general to you MacFee.
Please don't link every little ache and pain to diabetes. It's irrelevant whether or not it is, at this stage, because there are a couple of things that are important, and certainly one of them would significantly improve the likelihood of your plantar fasciitis healing and staying that way. But, both the things you need to do are important for your diabetes too, so could be a win:win.
In no particular order getting your bloods in order and dropping some weight.
In reality, even if those things didn't (in the time it takes to achieve) improve your heel, then it is undoubtedly tru e that you would be better placed, physically, to face surgery, if it became necessary.
But, please, please, don't link everything to diabetes. Personally, I find that to be such a dangerous position as it can lead to flawed at worst, or delayed proper diagnosis.
Good luck with it all.