Does metformin need to be routinely held in the hospitalized patient?
Metformin is a widely prescribed oral medication used in the management of type 2 diabetes mellitus. It is routine practice to hold metformin in the hospitalized patient due to risk of metformin-associated lactic acidosis (MALA). A recent publication by the Journal of Hospital Medicine addresses this common practice.
Key points:
- Metformin shunts metabolism towards anaerobic respiration, increasing production of lactic acid. Metformin is renally cleared and the risk of developing MALA increases with renal impairment.
- Given that acute kidney injury (AKI) is a common inpatient condition (20% of all inpatient and 50% of intensive care patients) as well as the disease states that increase risk of AKI, metformin is reflexively held by clinicians for all hospitalized patients.
- MALA is exceedingly rare. Since an initial report of 47 cases of MALA to the FDA, repeated studies and systematic reviews have disputed the link between metformin and lactic acidosis, particularly in the absence of significant risk factors or in patients with an eGFR > 30 mL/min/1.73 m2.
- Holding metformin poses risk of harm. Continuing metformin maintains steady blood glucose control and the practice of replacing metformin with correctional insulin monotherapy increases risk of hyperglycemia and is associated with increased length of stay.
- Clinicians should thus consider continuing metformin in all hospitalized patients in the absence of the disease states that increase risk of MALA and contrast-related indications. These include:
- High risk for or currently suffering from decompensated heart failure, severe sepsis, or other disease states resulting in hypoxia or tissue hypoperfusion
- An eGFR <30 mL/min/1.73 m2 or AKI; resume metformin when the AKI resolves
- COVID‐19 infection, until the risk of hypoxia has resolved
- IV contrast study in the presence of acute renal failure or an eGFR <30 mL/min/1.73 m2; resume metformin 48 hours after contrast administration.
- Intra‐arterial catheter study that might result in renal artery emboli; resume metformin when renal function normalizes.
Cohen DA, Ricotta DN, Parikh PD. Things We Do for No ReasonTM: Routinely holding metformin in the hospital. J Hosp Med. 2022;17:207‐210. doi:10.12788/jhm.3644
- Andrew Tout, PGY3