My grandmother's homemade turkey gravy consisted of browning some flour in a cast iron pan, adding onion and browning, and then the turkey drippings (no other ingredients, not even salt) and letting it simmer and cook away.

I guess the onions could be a source of "sugar".

It sure tasted good but these days, I just use some turkey drippings if I want to put something over my turkey. Don't usually even bother doing that. Plain turkey is fine with me.