Hi Donna!
I would think if metformin has any affect on liver, it would be to help it out, but I'm not a doctor.
Have you ever read Jenny Ruhl's blog? She writes on metformin quite frequently. Here's a link to a "metformin" search on her blog. You'll find the first article interesting, as half way down, she describes how she inexplicably started to gain, restarted metformin and started losing again.
http://diabetesupdate.blogspot.com/search?q=metformin

Try the metformin xr (extended release). You'll probably have to specifically ask your doctor to prescribe it, they all prescribe the regular otherwise. Also, ask for 500mg tablet size, that's the size that's covered by most pharmacies $4 plans. Also, even with the xr, build up your dose slowly. If he prescribes 1500, take 500 for a week, then 1000 for a week, then 1500. If you get the xr and build up, hopefully you'll avoid the tummy troubles.

I think it's worth a try!