Reports of Lactic Acidosis Attributed to Metformin, 2015–2018

James H. Flory, Sean Hennessy, Clifford J. Bailey, Silvio E. Inzucchi

Research output: Contribution to journalArticlepeer-review


OBJECTIVE: In 2016, the U.S. Food and Drug Administration (FDA) revised metformin's label to permit use in patients with mild-moderate chronic kidney disease. We sought to determine whether this change was associated with increased reports of metformin-associated lactic acidosis (MALA) to the FDA's Adverse Event Reporting System (FAERS).

RESEARCH DESIGN AND METHODS: Publicly available FAERS reports were analyzed.

RESULTS: MALA reports increased from 521 in 2015 to 1,939 in 2018. After restriction to U.S. reports, absolute and relative increase in MALA reports was less, from 111 to 243. The proportionate reporting ratio (PRR), a measure adjusted for rates of other adverse event reports, was stable.

CONCLUSIONS: The increased reports deserve attention, but the PRR's stability and FAERS's known limitations, including lack of a denominator or control group, do not permit the conclusion that U.S. MALA rates have increased. Further study with more robust data sources is needed.

Original languageEnglish
Pages (from-to)244-246
Number of pages3
JournalDiabetes Care
Issue number1
Early online date9 Oct 2019
Publication statusPublished - 1 Jan 2020

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© 2019 by the American Diabetes Association.
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