RT Journal Article SR Electronic T1 Metformin-associated lactic acidosis JF BMJ Case Reports JO BMJ Case Reports FD BMJ Publishing Group Ltd SP e239154 DO 10.1136/bcr-2020-239154 VO 14 IS 7 A1 Emma Jane Fadden A1 Christian Longley A1 Tushar Mahambrey YR 2021 UL http://casereports.bmj.com/content/14/7/e239154.abstract AB A 58-year-old female with known type 2 diabetes mellitus continued to take her usual medications, including metformin, an ACE inhibitor and a non-steroidal anti-inflammatory drug, while suffering from diarrhoea and vomiting. On presentation to the emergency department, she was found to have a profound lactic acidosis, cardiovascular instability and acute kidney injury. Despite a pH of 6.6, lactate of 14 mmol/L and a brief asystolic cardiac arrest, supportive treatment and the use of renal replacement therapy resulted in rapid improvement in her acid–base abnormalities and haemodynamic parameters. Metformin-associated lactic acidosis is a rare but life-threatening complication of diabetes management. Patient education and awareness amongst clinicians are paramount in the prevention and treatment of this condition.