When the FDA approved metformin in 1994, they attached a boxed warning that cautioned against use of the drug in people who had even the slightest bit of abnormal kidney function, that is, men who had serum creatinine at or above 1.5 mg/dL and women who had serum creatinine at or above 1.4 mg/dL. Metformin inhibits creatinase, resulting in false-low urinary creatinine values. The inhibition of metformin may occur even at a low creatinine level. Dilution of urine samples may be useful for decreasing the effect of metformin. Discover metformin use in CKD with renal dosing guidelines, safety considerations, and risk management strategies for patients with kidney impairment. Direct Recommendation Metformin can be safely used in patients with type 2 diabetes and chronic kidney disease when eGFR is ≥30 ml/min/1.73 m², with mandatory dose reduction to 1000 mg daily when eGFR falls between 30-44 ml/min/1.73 m², and discontinuation required when eGFR drops below 30 ml/min/1.73 m². 1, 2, 3 Metformin is the first pharmacological option for treating type 2 diabetes. However, the use of this drug is not recommended in individuals with impaired kidney function because of the perceived risk of lactic acidosis. We aimed to assess the efficacy and safety of metformin in patients with type 2 diabetic kidney disease (DKD). Metformin is generally not recommended for individuals with an eGFR below 30 mL/min/1.73m², as this indicates severe kidney impairment. In such cases, metformin is considered contraindicated. Continuing metformin with an eGFR below this level significantly increases the risk of drug accumulation. Metformin, a common diabetes medication, affects kidney health, leading to updated guidelines on creatinine levels. Patients must regularly monitor their kidney function to ensure safe usage, reducing the risk of complications. The use of metformin is contraindicated in men and women with serum creatinine concentrations of 1.5 mg/dL or higher and 1.4 mg/dL or higher, respectively, due to the risk of the life-threatening complication, lactic acidosis. Today’s U.S. Food and Drug Administration prescribing guidelines for metformin contraindicate its use in men and women with serum creatinine concentrations ≥1.5 and ≥1.4 mg/dL (≥132 and ≥123 µmol/L), respectively. The straightforward answer is that metformin itself does not directly increase serum creatinine levels. The drug does not cause muscle breakdown or produce substances that would artificially raise creatinine in the bloodstream.