Metformin and B12 Deficiency: A Bigger Problem Than We Thought

Hello. I'm Dr Charles Vega, and I am a clinical professor of family medicine at the University of California at Irvine. Welcome to Medscape Morning Report, our 1-minute news story for primary care.

Patients taking metformin should have their vitamin B₁₂ levels assessed regularly to avoid peripheral nerve damage.

That's the conclusion from a single-center observational study^[1] of more than 150 women conducted in the United Kingdom. On average, the women were 63 years old, were taking 2000 mg/day of metformin, and had been on the drug for about 6 years.

The majority of the women had not had their B₁₂ levels measured. However, upon testing, almost 1 in 10 were found to have a B₁₂ deficiency.

Although metformin is recommended for the first-line treatment of type 2 diabetes, it is associated with vitamin B₁₂ deficiency, which itself increases the risk for peripheral neuropathy. Current guidelines do not recommend routinely checking B₁₂ levels, although the British Society of Hematology recommends checking if there is a strong clinical suspicion.^[2] Many patients with diabetes have peripheral neuropathy, and treatment with vitamin B₁₂ in cases of deficiency can give clinicians something proactive with which to treat it.

Prior research has concluded that routine testing would not be cost-effective or clinically useful for people using this medication, but the authors of this study argue that it is time for that to change. While this one study may not warrant a guideline change, it is certainly something for those of us in clinical practice to keep in mind.

Any views expressed above are the author's own and do not necessarily reflect the views of WebMD or Medscape.

Cite this: Metformin and B12 Deficiency: A Bigger Problem Than We Thought - Medscape - Dec 18, 2018.

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