Just got a message that you were looking for a vet in the Atlanta area...
I use a feline only practice in Roswell (north side of ATL) called The Cat Clinic. It is run by Dr. Michael Ray and I really, really like him. You can find their info here:
http://catclinicofroswell.com.
They see a number of diabetic cats and seem to have very good success with treating them. I have also found them very respectful of owners who want to be hands-on and involved in their cat's care.
Let me know if there is anything else I can do to help.
Susan