Metformin is excreted in its original form via the renal tubules, where its clearance is 3.5 times higher than that of creatinine, and is not inherently damaging to the kidneys. Metformin is excreted through the kidneys, and severe renal insufficiency can lead to accumulation of metformin in the body, with the risk of exacerbating lactic acidosis. The International Diabetes Federation IDF recommends that metformin is contraindicated in eGFR <30 ml/min (severe renal failure). For patients who need to take metformin, it is recommended to actively visit the hospital and develop appropriate usage and dosage with the help of a doctor, and patients need to avoid blindly using the drug on their own.