Could Metformin cause thinning or hair loss? I started two Metformin 500 mg a day last May. Went on a locarb, no processed foods or alcohol diet. Lost 30#'s. End of August, switched to one Metformin ER 500 mg a day cause my A1C went from 7.4 down to 5.2 in 3 1/2 months. I have thought of a vitamin or iron deficiency, but I eat a lot of healthy foods and haven't lost weight beyond the 30#'S I lost last summer. I read that some people on here think Victoza caused their hair loss. I'm 68 so maybe it's due to aging. Will ask my dr when I see him the end of April for an A1C test.