Metformin seems to lower vitamin B12 levels in diabetics.

A Canadian prospective case-control study has found that Vitamin B12 levels were significantly lower in type-2 diabetics taking metformin than those not taking it (231 vs. 486 pmol/L). Those on metformin also had significantly higher levels of two markers of B12 deficiency (homocysteine and methylmalonic acid) along with increased severity of neuropathy. This B12 deficiency may exacerbate the symptoms of neuropathy in diabetics. It is unknown yet if metformin interferes with B12 deficiency or if or supplements would be beneficial.

PositiveTip: A good diet, regular physical activity, and a healthy weight remain the best defense against type-2 diabetes.