Chalup, whilst low carb is likely to help Sean with his high numbers, which could improve the headaches, as others have suggested, it's not the only thing that could be causing them.
@Sean-W - If you are due to restart your medication today, the it makes sense to crack on and do that and see what happens over the next day or so. The Glaucophage takes a while to build to it's most effective state, but the Gliclazide should have a bit of an impact on your numbers quite quickly.
However, it's important not to ignore headaches without knowing what is causing them. It could just be your body being stressed by your higher numbers, but it could also be an array of other things. I'm not posting that to scare you; just saying headaches happen for a huge number of reasons.
I hope things improve for you.