From the Research
Metformin (Glucophage) is generally considered safe for patients with G6PD deficiency. Unlike some medications that can trigger hemolytic anemia in G6PD-deficient individuals, metformin does not cause oxidative stress to red blood cells and has not been associated with hemolytic reactions in these patients, as supported by a recent study 1. Metformin works by decreasing glucose production in the liver, improving insulin sensitivity in peripheral tissues, and reducing intestinal glucose absorption—mechanisms that don't interact with the G6PD pathway.
Key Considerations
- The standard dosing of metformin (starting at 500 mg once or twice daily, potentially increasing to a maximum of 2000-2550 mg daily divided into 2-3 doses) can be followed in G6PD-deficient patients without special adjustments, according to the most recent and highest quality evidence available 1.
- Normal metformin precautions still apply, including monitoring kidney function since the medication is contraindicated in patients with significantly reduced renal function (eGFR <30 mL/min) and requires dose adjustment for moderate renal impairment.
- Patients should be informed about common side effects such as gastrointestinal disturbances, which typically improve over time, and the rare but serious risk of lactic acidosis, particularly in those with kidney, liver, or heart failure.
- Although there have been rare case reports suggesting metformin-induced hemolytic anemia in G6PD-deficient patients 2, the majority of evidence, including a recent real-world study 1, supports the safe use of metformin in this population.
Clinical Guidance
- Clinicians should be aware of the potential, though rare, risk of hemolytic anemia in G6PD-deficient patients taking metformin, as highlighted by a case report 2.
- However, the benefits of metformin in managing diabetes often outweigh the risks, and its use should not be avoided solely based on G6PD deficiency, as indicated by a comprehensive review 3 and a guideline update 4.
- Monitoring for signs of hemolysis and adjusting treatment as necessary is prudent, but metformin can be a valuable therapeutic option for G6PD-deficient patients with diabetes, supported by the latest clinical pharmacogenetics guidelines 4.