I have a problem with hair loss too and am taking Metformin. I think the hair loss may have started at around the time I started with Metformin but I never made the connection. I haven't seen it listed as a side effect. My hair is getting really thin now.
I am taking some vitamins and minerals and there is some sign of regrowth according to my hairdresser. I will give you details if you want to try them too. But what may work for me (I don't know yet) may not work for you of course.
There is a thread called Metformin Questions and Answers which contains more about hair loss which is where this thread will probably end up.