HbA1C is frankly an utterly useless way of measuring how well you're doing because as has been pointed out it can easily be swayed one way or another by compensating for those lows with a couple of highs or regularly being slightly above your recommended range or vice versa. I had a great HbA1C myself according to the nurse back in December despite waking up low just about every single day for 6 months straight and feeling horrible on a daily basis, and I pointed out that the numbers don't really tell the same story once you actually analyse them, which she agreed with.
Until there is a way of keeping track of when and why we get our highs and lows, I expect we'll be stuck using these useless methods however. I'm working on my own theory to solve the problem, but it's not gonna be useful(if it works) for quite some time.