I have been on 1000mg metformin twice daily (told to take with food) since I was diagnosed with type 2 in 2006. I don't know if the metformin had anything to do with my low B12, or if it was something to do with my diet, or the many medications I take to control my myeloma.
Just recently I was asked to repeat a routine blood test to confirm that my B12 was within acceptable levels. Having had the blood test I received a text from my GP practice stating my B12 was rather on the lower end to spectrum, and I love this bit, "you are not eating enough red meat, or drinking enough milk"! I love red meat and I drink milk almost by the gallon. When I read the text to my wife, she nearly fell to the floor in hysterics.
The serious part of this for me, was that I was unaware low consumption of red meat and milk could have this affect on my B12 levels. I know taking a B12 supplement.