As a combination of active forms of folic acid, vitamin B6, and vitamin B12, Metanx® may help improve certain complications of diabetes. Specifically, this prescription vitamin is used as a dietary supplement in people who have certain blood vessel problems associated with diabetic peripheral neuropathy. It may also be used in people who have hyperhomocysteinemia (high levels of homocysteine in the blood), especially for people with leg or foot ulcers (open sores or wounds)