Initially, my type 2 diabetes was treated with 80 mgs gliclazide at breakfast. I suffered no gastrointestinal disturbances. As my health improved with LCHF, I managed to halve the dose to 40 mgs. Eventually, I weaned myself off gliclazide altogether by reducing my carbohydrate consumption further.
When first prescribed 2 x 500 mgs metformin, I experienced some nausea following my evening dose. The nausea returned briefly when the dose was raised to 3 x 500 mgs and when maxed out on 4 x 500 mgs, I experienced nausea once more following my evening dose.