If your A1C is below 7.0 that is under control. Below 6.0 it is considered very good. At 5.0 it is considered excellent.
True, but just as food for thought, please consider the link below. Agree or not, I know you'll find all of it of great interest, especially the A1C part: http://chriskresser.com/when-your-“normal”-blood-sugar-isn’t-normal-part-2 I'm just shooting for the lowest I can get it (at this rate I'm on my way).
I remember when mine was at 5.4 and that was years ago before some interactions with the medications began to cause changes. As the article stated the A1C is not an accurate predictor of diabetics alone. The longer you keep it around that good baseline the better off you will be. Good fortune on the quest for sugar control.