Yes Ally, I've been taking metformin for a few months now and I have noticed an increase in bruising. I hadn't made any connection with metformin though until I read your post. I am also taking warfarin which is known to cause bruising too, so I had assumed it was just because of that, but my blood has not been too thin for several months so now I believe the metformin may have made things a little worse too. I currently have five bruises on my arm (from a thumb and four fingers) where someone gently held my arm one day last week.