I have been taking Metformin for 15-20 years. I recently (last 3 years) have been told that I am B12 deficient and have injections every 12 weeks. Metformin can make you B12 deficient. This seems crazy to me! Is there an alternative diabetic medication that can do the same job as Metformin without making you B12 deficient? I am also on 34 units of Lantus long-acting insulin daily.