Metformin Contraindications and Precautions

Introduction to Metformin Contraindications

The American Diabetes Association recommends that metformin can be used in patients with eGFR ≥45 mL/min/1.73 m² with standard dosing and monitoring every 3-6 months 1, 2
The FDA guidelines, as noted by Diabetes Care, suggest that metformin should not be initiated in patients with eGFR 30-45 mL/min/1.73 m², and its use should be reassessed in those already on it, considering dose reduction or discontinuation 1

For patients with eGFR <30 mL/min/1.73 m², metformin is absolutely contraindicated due to the risk of lactic acidosis 1
The American Association of Clinical Endocrinologists emphasizes the importance of using eGFR instead of serum creatinine for assessing renal function in patients on metformin 1

The American Association for the Study of Liver Diseases states that metformin is contraindicated in decompensated cirrhosis (Child-Pugh class B or C) because of the increased risk of lactic acidosis 3
In patients with compensated cirrhosis (Child-Pugh A) and eGFR ≥45 mL/min/1.73 m², metformin can be used safely with monitoring every 3-6 months 3

The American College of Physicians guidelines, as referenced in Diabetes Care, recommend discontinuing metformin during any hospitalization or acute illness that could compromise renal or hepatic function 4, 5
Conditions requiring immediate discontinuation of metformin include any hospitalization, sepsis, serious infections, dehydration, acute heart failure with hypoperfusion or hypoxemia, and acute kidney injury 3, 4, 5

The American Heart Association notes that metformin is contraindicated in acute or decompensated heart failure with hypoperfusion or hypoxemia 4, 3
However, in stable, compensated heart failure, metformin can be used with caution, as indicated by the KDOQI guidelines 6

The American Geriatrics Society suggests that advanced age alone is not a contraindication to metformin, but elderly patients require more frequent renal function monitoring 2
The American Diabetes Association recommends that metformin should not be used during pregnancy, and insulin is the preferred agent 4

The European Association for the Study of Diabetes emphasizes the importance of calculating eGFR instead of relying on serum creatinine levels to avoid misleading results in certain patient populations 1
Educating patients on "sick-day rules" to hold metformin during acute illness at home with vomiting, diarrhea, or reduced oral intake is crucial, as highlighted by Praxis Medical Insights 3
The default position should be to discontinue metformin on hospital admission unless there is a compelling reason to continue, with daily monitoring, as suggested by the Society of Hospital Medicine 5