Common Diabetes Drug Linked to Vitamin B12 Deficiency

Metformin, a common diabetes drug, is linked to vitamin B12 deficiency when used over the long term, according to a new study.

Although metformin treatment has been linked to B12 deficiency previously, few studies have explored the risk of its long-term use.
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To conduct their study, researchers analyzed data from the Diabetes Prevention Program (DPP) and the DPP Outcomes Study (DPPOS), which included patients aged 25 years and older with high glucose levels from 27 clinics in the United States. The study followed these patients for more than 10 years.

 A total of 2155 patients were randomly assigned to receive either 850 mg of metformin twice daily or a placebo for 3.2 years. After that, the metformin group received open-label metformin for another 9 years.

Researchers took a blood sample from patients after 5 years and 13 years.

After analyzing the data, researchers found that those in the metformin group had lower B12 levels at 5 years and 13 years than those in the placebo group.

Although B12 level wasn’t influential, anemia was more prevalent among those in the metformin group. However, those in the metformin group who had low B12 levels were more likely to have neuropathy.

“Long-term use of metformin in DPPOS was associated with biochemical B12 deficiency and anemia,” researchers concluded. “Routine testing of vitamin B12 levels in metformin-treated patients should be considered.”

—Amanda Balbi

Reference:

Aroda VR, Edelstein SL, Goldberg RB, et al. Long-term metformin use and vitamin B12 deficiency in the diabetes prevention program outcomes study. JCEM. Published online February 22, 2016. http://dx.doi.org/10.1210/jc.2015-3754.