my doc says Byetta is safer for liver people.
I took lantus throughout treatment. However, my doctor pulled me off metformin because it sometimes messes with ALT levels, making it difficult to get an accurate picture of how liver enzymes respond to tx. I ate so little during tx, and a lot of it was ice cream. Nevertheless, for some reason - despite all the sugar in ice cream - my A1c was better during tx than it ever was before or after. Now, a year since finishing, I'm back on metformin and my ALT and ASt are wonderfully low (21 and 26 respectively).
I do know of people who kept up with the metformin throughout tx and did just fine. It's kind of questionable whether stopping it is necessary.