March 20, 2016
Metformin Does Cause B12 Deficiency
Allen called me shortly after he read this. I say shortly because he knows I sleep late and he does respect my sleep time. He was surprised that it has taken this long to publish something we have known for a long time. He knew that I would be busy for most of the afternoon and again the following day, but felt this was important enough to remind me of it and ask that I blog about it. Then he asked if I could meet with Ben, Barry, and him on Saturday. I agreed and was happy to do this.
When I arrived, they were waiting for me. Allen had printed a copy for me and asked if I had read it. I told him that I had and would be blogging about it after March 18. Barry said you already have posts that far out and I said yes. Plus, I have three other blogs ready to post and about 18 more topics I want to write in the weeks ahead. Ben said yes, there have been many topics of interest lately. I said I wish I had time to write about all the topics that interest me.
People taking metformin, one of the safest type 2 diabetes medications, for several years may be at heightened risk of vitamin B12 deficiency and anemia, according to a new analysis of long-term data. Allen knows this from first hand experience and others of us know this because our vitamin B12 levels were low and we cannot absorb what we need from the foods rich in B12.
Metformin helps to control the amount of sugar, or glucose, in the blood by reducing how much glucose is absorbed from food and produced by the liver, and by increasing the body’s response to the hormone insulin, according to the National Institutes of Health.
The study used blood samples and the researchers found that at year five, average B12 levels were lower in the metformin group than the placebo group, and B12 deficiency was more common, affecting 4 percent of those on metformin compared to 2 percent of those not taking the drug.
Borderline low B12 levels affected almost 20 percent of those on metformin and 10 percent of those taking placebo.
Average vitamin B12 levels were higher by year 13 than in year five, but B12 deficiency was also more common in both the metformin and placebo groups, as reported in the Journal of Clinical Endocrinology and Metabolism. The down side of being vitamin B12 deficient can mean nerve damage that is severe and may be irreversible. Severe and prolonged B12 deficiency has also been linked to impaired cognition and dementia. It can also cause anemia (low red blood cell count), but fortunately, this condition is reversible with treatment. Another finding of the study was more people in the metformin group were also anemic at year five than in the placebo group.
Humans do not make vitamin B12 and need to consume it from animal sources or supplements. Vegetarians may get enough from eating eggs and dairy products, but vegans need to rely on supplements or fortified grains.
Doctors who prescribe metformin to patients long-term for type 2 diabetes, gestational diabetes, polycystic ovarian syndrome or other indications should consider routine measurement of vitamin B12 levels, the authors conclude.
People who are taking metformin should ask their doctor about measuring their B12 level. Restoring healthy B12 levels is easy to accomplish with pills or monthly injections.
Finally, the study authors say, “The risk of B12 deficiency should not be considered a reason to avoid taking metformin.”