Objective: We present a patient with metformin associated lactic acidosis, to remind of a potentially lethal adverse reaction. Methods Case study. Results This 74-year-old man had underlying disease and past history of type 2 diabetes mellitus (DM), chronic kidney disease (CKD), old myocardial infarction and coronary artery disease s/p percutaneous coronary intervention. He was admitted to the intensive care unit due to hypoglycemia, hyperkalemia, acute on CKD, metabolic acidosis, and lactic acidosis on June 9, 2018. Consider the cause of lactic acidosis, stable hemodynamics and acute on CKD were noted, Linagliptin/Metformin (2.5/850 mg) and Glimepiride/Metformin (2/500 mg) were used as current oral anti diabetic therapy, metformin associated lactic acidosis was diagnosed. After admission, we treated the patient with intravenous fluid for acute or chronic kidney disease and glucose water, and continue coronary artery disease medication. The patient's consciousness was good and appetite improved. ABG showed normal PH value and laboratory date showed that lactate was in normal range. Blood sugar level was improved. Under the stable condition, he was discharged uneventfully on June 18, 2018. Conclusion Metformin is commonly used in type 2 DM. Lactic acidosis is a potentially life-threatening metabolic disorder. Metformin associated lactic acidosis must be considered in obscure metabolic acidosis in diabetic and CKD patients. Metformin should only be prescribed if the contraindications, in particular renal failure are carefully monitored. UK’s National Institute for Clinical Excellence guidelines advise that metformin should be reviewed if the serum creatinine exceeds 130 μmol/l [or estimated GFR (eGFR) is below 45 mL/min/1.73 m2], and stopped when creatinine rises above 150 μmol/l (or eGFR falls below 30 mL/min/1.73 m2).
