On the leaflet that comes in my Glucophage (metformin) box it states that drinking alcohol when taking metformin is not advised as it increases the chances of suffering lactic acidosis particularly if you already suffer from a liver condition.
I was able to find the following on the net
"Too much consumption of alcohol while taking a type 2 diabetes Metformin medication is highly discouraged. A person who drinks alcohol exposes himself to a potentially fatal condition known as lactic acidosis. It occurs when lactic acid accumulates in the body and it is difficult for the body to neutralize it rapidly. The patient may show symptoms such as vomiting, nausea, low BP, or high pulse rate when this condition attacks. Seek immediate medical attention when lactic acidosis is diagnosed - See more at:
http://metforminfacts.com/metformin-alcohol/#sthash.345rB68j.dpuf
Sorry to be a spoilsport.
Pavlos