Here is a link for cat foods:
http://www.petfoodratings.net/cattable.html

I feed Taste of the Wild, which is a grain free food. There are several out there.

As for what a diabetic cat can / should eat, I have no info.
You can use Google and put in
diabetic cat food brands

that give lots of hits for info.

You can also use Google for a diabetic pet forum.
I think on Catster there is also a diabetic forum.

Are you testing blood sugars twice daily? Is the cat on insulin, or other meds?

Best wishes!