Vitamin B12 deficiency can lead to cognitive impairment and dementia as well as fatigue and nerve damage. A new study shows that one of the most common diabetes medications, metformin, increases the risk of this nutritional deficiency.
How Metformin’s Effect Was Studied:
Over 3,000 adults at high risk for type 2 diabetes were enrolled in the Diabetes Prevention Program. They were randomized to receive metformin or placebo.
Blood was drawn at five and 13 years after the start of the study. Average vitamin B12 levels were lower among participants on metformin at the five-year mark. More alarming, vitamin B12 deficiency was twice as common among those taking metformin, affecting 4 percent of the participants compared to 2 percent of those on placebo. 20 percent of metformin users had borderline low levels of this vitamin. Similar trends were seen at year 13.
Our Advice:
People who are taking metformin should have their vitamin B12 levels monitored regularly. We don’t think people should refuse to take metformin because of this potential complication. It has a number of very useful benefits, including weight control and cancer prevention. But it definitely makes sense for metformin users to be on the lookout for the problems it can cause.
Journal of Clinical Endocrinology and Metabolism, online, Feb. 22, 2016
