From the Guidelines
Metformin should be discontinued in patients with lactic acid levels above 1.8 mmol/L due to the increased risk of lactic acidosis, as evidenced by a recent study published in The Lancet Diabetes and Endocrinology 1. This recommendation is based on the potential for metformin to cause lactic acidosis, particularly in patients with risk factors such as impaired renal function, liver disease, or conditions that impair lactic acid clearance.
- Key factors to consider when deciding to discontinue metformin include:
- Lactic acid levels above 1.8 mmol/L
- Impaired renal function, particularly an estimated glomerular filtration rate (eGFR) less than 30 mL/min per 1.73 m²
- Liver disease or other conditions that impair lactic acid clearance
- Presence of risk factors for lactic acidosis, such as acute kidney injury, hypoxia, or shock
- Alternative glucose-lowering medications, such as insulin, DPP-4 inhibitors, or SGLT2 inhibitors, may be considered for glycemic control while metformin is discontinued 1.
- Regular monitoring of renal function and lactic acid levels is essential when considering restarting metformin therapy, especially in patients with risk factors for lactic acidosis.
- The decision to restart metformin should be based on the individual patient's risk-benefit profile, taking into account the potential benefits of metformin on glycemic control and the risk of lactic acidosis, as reported in a study published in The Lancet Diabetes and Endocrinology 1.
From the FDA Drug Label
If metformin-associated lactic acidosis is suspected, general supportive measures should be instituted promptly in a hospital setting, along with immediate discontinuation of metformin hydrochloride tablets The answer to whether to continue metformin with a lactic acid level above 1.8 is no, the medication should be discontinued.
- Lactic acidosis is a serious and potentially fatal condition.
- The FDA label recommends immediate discontinuation of metformin if lactic acidosis is suspected.
- Elevated lactate levels (>5 mmol/L) are a characteristic of metformin-associated lactic acidosis.
- Patients with renal impairment are at increased risk of metformin-associated lactic acidosis 2 2.
From the Research
Lactic Acidosis and Metformin Use
- Lactic acidosis is a rare but potentially fatal complication of metformin use, particularly in patients with renal impairment 3, 4, 5, 6.
- The risk of lactic acidosis is increased in patients with renal function <60 mL/min/1.73 m(2) 5.
- Elevated plasma metformin concentrations, often due to renal impairment, and secondary events such as sepsis, cirrhosis, or hypoperfusion, can contribute to the development of lactic acidosis 4.
- Continuous renal replacement therapy (CRRT) may be effective in treating lactic acidosis by eliminating metformin, correcting acidosis, and maintaining fluid balance 3, 7.
Management of Lactic Acidosis
- Prevention is a key factor in managing lactic acidosis, and patients should be aware of the risks and benefits of continuing metformin therapy 3.
- Renal function should be adequately monitored, and the dose of metformin should be adjusted if necessary, if renal function falls below 60 mL/min/1.73 m(2) 5.
- The decision to start renal replacement therapy (RRT) should be based on individual patient factors, including lactate level and SOFA renal and cardio score 7.
Continuing Metformin Therapy
- The risk of lactic acidosis hospitalization is uncommon and not statistically different between patients who continue metformin and those who continue sulfonylureas 6.
- Patients with severe lactic acidosis may have a higher mortality rate, even with RRT, emphasizing the importance of addressing underlying conditions 7.
- The benefits of metformin therapy, including significant mortality reduction and lower progression towards end-stage renal disease, should be weighed against the risks of lactic acidosis 3.