There is a warning that taking any alcohol whilst on Metformin should be avoided, but having said that I personally, like many other have taken it and not found any problems.
You will need to be careful in what you drink (beers are usually best avoided) though most spirits and wine (red) in particular can in moderation be beneficial.
Watch the fortified wines as many have a high alcoholic content and never drink on an empty stomach.
Well im on Metformin and although i have changed my diet,increased exercise and basically lived like a monk,im dammed if i will stop drinking .I work hard,have never smoked and have no other vices.But i love whisky and i think if i allow myself a few,then why not?I know this may sound stupid,but im sure if i dont go mad and make sure i eat well,i can be ok.