Awww, poor kitty and poor you. I know how hard it is when they get old, facing that with two cats of mine own right now. I own other animals but my cats own me, I have always been a "cat person". You gave her a good life...she was smart...she stayed on the deck and she knew she found a good home. Sometimes the rescues are the best pets ever. Hoping for good news.
Not a cat person by any stretch, unless they are all lovey and crawl up in my lap looking for attention (Cumon folks, even cat haters can't turn that away!). Hope it's nothing too serious and that she can recoup and be around for you for another few years.
She did have a slightly elevated temp, so the vet gave some antibiotics and an anti-inflammatory. And now there is some pus draining out from somewhere we can't find the exact spot. So, it appears there was some type of abscess that is draining out. So, the antibiotics was probably a good call.
An abscess would be much better than diabetes. Might have to sedate her and shave the leg to find the wound. But if it is draining then hopefully it will clear up with the drugs. My cats usually lick the wound (if they can reach it) and will help keep it draining.