My levels are pretty good and I rarely hypo. They will literally go through every reading for the last 3 months ( well, they did with me ). If they see a low reading, they will ask you about it and they will look at the next reading to ensure you treated it. Their main priority is to satisfy themselves that you test regularly and remain hypo aware. Obviously, they will expect you to know DVLA testing rules, 30mins prior to driving, test every 2 hrs etc. All the info is available on-line.