Metformin may cause B12 deficiency contributing to seriousnerve damage in diabetics

June 09, 2009

The popular diabetes drug metformin may contribute to vitamin B12 deficiency, according to a new study. This is not news; previous studies have found that metformin depletes two important B-complex vitamins, folic acid and B12. Both are needed for mental health, to decrease the rate of mental deterioration with aging, to create hemoglobin and red blood cells, to protect the heart and circulation and to decrease the risk of various cancers but this new research opens a new window on possible consequences of b12 depletion due to metformin use; deterioration of the nervous system. The researchers found that 40% of the diabetic patients using metformin had vitamin B12 deficiency or were in the low-normal range for the essential vitamin and that 77% of the metformin users with vitamin B12 deficiency also had peripheral neuropathy; a common form of nerve damage seen in type 2 diabetics.

The study performed by researchers at the University of Texas Health Science Center looked at the prevalence of vitamin B12 deficiency in 76 people with type 2 diabetes who had been taking metformin for at least one year. The results showed that more than three-fourths of metformin users who had low vitamin B12 levels also had evidence of peripheral neuropathy.

Peripheral neuropathy is a type of nerve damage most often characterized by pain, tingling, and numbness in the hands and feet. Diabetics with peripheral neuropathy have an increased risk of amputation. Because peripheral neuropathy is such a major complication of diabetes, researchers say the results suggest that people using metformin be screened for vitamin B12 deficiency or supplemented with vitamin B12. Also, anyone already diagnosed with peripheral neuropathy that uses metformin should be screened for vitamin B12 deficiency. The study was presented at the American Diabetes Association’s 69th Annual Scientific Sessions this week.