It seemed to be rough on my GI. My Dr. who knows very little about Diabetes switched me to Glimipremide.That worked but after reading bad things about it just switched back to metformin.2 500mg a day. It doesn't seem to be working like it use to 200 readings a few times . Could it just take a while to build up in my system ,or do you think the glimipremide may have made me require a higher dose.Because I need knee and hipreplacement my exercise level has dropped in recent weeks.I never had readings of 200 before ,how damaging is this?