Conventional medical wisdom says A1c under 7 = controlled diabetes.
Most people in the DOC believe that controlled diabetes is the A1c of a non-diabetic, though, so A1c under 6, not under 7.
But in the end, the A1c is just one measure. You can be 6.5 with stable BGs in the 80s-140s and you can be 6.5 with wild swings between 50-200, you know? Clearly the person in the first case has good control and the person in the second case is "out of control". They'll have the same A1c, but the one going to the 200s on a regular basis (like me... my A1c is 6.5 too, and trust me, I do not have control yet...) will have difficulty healing.