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GLUCOPHAGE and subnormal vitamin B12 in 29-week trials

3 min read · Reviewed 5 October 2026, 07:46:40 UTC

Medically reviewed by Dr. Priya Natarajan, MD - Clinical pharmacology, Dublin

Metformin tablets beside a vitamin B12 blood request form

01Vitamin B12

In GLUCOPHAGE clinical trials of 29-week duration, a decrease to subnormal levels of previously normal serum vitamin B12 was observed in approximately 7% of patients. That decrease may be associated with anemia. It appears to be rapidly reversible with discontinuation of GLUCOPHAGE or with vitamin B12 supplementation. Hematologic parameters should be measured annually.

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Sources

FDA / Glucophage (metformin) prescribing information

Checked against the current label and reviewed by Dr. Priya Natarajan. See Pick → Check → Tag → Bin.