According to a study at Hucknall Road Medical Centre, Nottingham, patients with type-2 diabetes, taking metformin, should have their vitamin B12 levels assessed more regularly to avoid irreversible nerve damage. The study findings suggest that earlier detection of vitamin B12 deficiency through routine screening of all metformin-treated, type-2 diabetes patients could reduce their risk of developing irreversible, painful and potentially disabling nerve damage. Vitamin B12 is an essential nutrient that is not produced in the body naturally. This water-soluble vitamin is essential for many functions in your body. Besides keeping your nerves healthy, it also supports normal brain function and the production of DNA and red blood cells. You can easily get this vitamin from food sources. It is mainly found in animal products, especially meat and dairy products. Fortified foods are also good sources of this vitamin.