Hi! I was put on metformin because of my pre diabetes. Two months later I developed severe leg cramps and twitching, my hands and legs are tingling. My doctor told me to take 1,000 mcg of b12. Well my cramps stopped but not the tingling and twitching. I don't think it's enough. She says I should see a neurologist because she "never heard of" this happening to anyone who was on metformin (even though she told me to take b12!). I think I have a severe deficiency. How much b12 should I take to alleviate these symptoms? P.S. I have an appointment with a neurologist.