UMEM Educational Pearls

Category: Toxicology

Title: Observation for the development of metformin associated lactic acidosis after an acute metformin overdose

Keywords: meformin overdose, metformin associated lactic acidosis, observation period (PubMed Search)

Posted: 11/14/2019 by Hong Kim, MD, MPH
Click here to contact Hong Kim, MD, MPH

 

Metformin is one of the most commonly prescribed oral hypoglycemic agents. Metformin associated lactic acidosis (MALA) is uncommon but potentially life-threatening complication of metformin overdose. 

Lactic acidosis occurs due to inhibition of mitochondrial glycerophosphate dehydrogenase, resulting in decreased conversion of lactic acid to pyruvate.

A small retrospective study (using Illinois Poison Center data) attempted to characterize the development of MALA after an acute overdose.

MALA was defined as 

  • Lactate: > 5 mmol/L
  • Acidemia: (HCO3< 20 mmol/L or pH < 7.35)

Results

40 cases of MALA identified between Jan. 2001 to Dec. 2014

  • Meadian age: 41 year
  • Female: 55%
  • Acute on chronic ingestion: 62.5%
  • Hypoglycemia: 3 (7.5%)

Time to development of MALA (n=30)

  • <=6 hours: 18 (60%)
  • 6-12 hours: 9 (30%)
  • >12 hours: 3 (10%)
  • Unknown: 10

Death: 1 (2.5%)

 

Conclusion

  1. The majority of MALA developed within 6 hours. However, delayed onset of MALA can occur, up to 12 hours post ingestion.
  2. Minimum of 12 hour of observation is recommended after an acute metformin overdose.

References

Jillian Theobald, Jamie Schneider, Navneet Cheema & Carol DesLauriers (2019) "Time to development of metformin-associated lactic acidosis," Clinical Toxicology, DOI: 10.1080/15563650.2019.1686514