There's lot of info about metformin around. I've taken it since my Dx- it has never given me any problems. I always take it with food. I take it with breakfast and dinner. Also before bed to help with the Dawn effect (2000 mg total). Some generics smell like rotting fish (from my WalMart), others are virtually odor free.
I'm on a really low dose, and only once a day, so I haven't had any side effects. I started out on double the dose, but felt weak on my low carb diet, so doc cut it in half. Since then I haven't had any problems.