I have very active work outside in the desert sun, and when I started 5 years ago it was hell on earth. I was used to being in an office most of the time and in my house the rest of the time. The only heat I got was on the way to or from my car. Now I'm out in in all day and I still say "This really sucks!" but I don't feel it anywhere near as badly as I used to.
It's going to take some getting used to, but I can't see there being any other way besides just doing it. I kind of see heat tolerance like building up muscle. If you don't ever use it, your body doesn't think you need it.
My advice would be to make sure you stay hydrated AND keep your electrolytes up, espcially if you're in Georgia where the humidity is going to make you sweat like crazy anyway. Coconut water is a little high in carbs if that's something you're worried about, but it works wonders for keeping the right mineral balance so you don't end up with a nasty headache or worse. And try just being in the heat for longer periods of time before you get into a full blown workout when the temps are high. It's going to take some time. Wish there was a way around it, but there isn't without causing some serious damage.
I'm not sure how the diabetes ties into this whole thing, but for some reason it wouldn't surprise me if that was an issue that needed some special consideration. Hopefully some of the others will have more information on that aspect.