A 72-year-old male patient whose personal history included a diagnosis of chronic obstructive pulmonary disease (COPD), arterial hypertension, type II diabetes mellitus and chronic ischaemia of the lower limbs. He was being treated with metformin, acarbose and glinclazide. He presented with a 72-hour history of diffuse abdominal pain accompanied by diarrhoea and anorexia, with subsequent deterioration of the level of consciousness. He was seen at a secondary hospital where he was found to have acute renal failure, significant metabolic acidosis and haemodynamic instability, which led to the decision to transfer him to the ICU of our hospital.
On arrival at our unit, the patient was conscious but sleepy, tachycardic (heart rate 120 beats per minute in sinus rhythm), hypotensive (blood pressure 80/40 mmHg) and with indirect signs of low cardiac output on physical examination. Among the analytical determinations made on admission, acute renal failure with creatinine and urea levels of 6.6 mg/dl and 197 mg/dl respectively and severe lactic acidosis with pH: 6.8, base deficit -29 mmol/l, GAP anion of 41 and lactate level of 176 mg/dl stood out.
Given the suspicion of acute metformin intoxication, a blood sample was taken to determine the plasma levels of metformin and treatment was started consisting of water and electrolyte replacement, haemodynamic stabilisation using noradrenaline at a dose of 0.4 mcg/kg/minute and dobutamine at a dose of 10 mcg/kg/minute and correction of the acidosis by intravenous administration of 1 M bicarbonate. In agreement with the Nephrology Department, haemodialysis was also decided.
The patient's evolution was favourable, with progressive disappearance of acidosis and normalisation of renal function parameters that allowed the patient to be discharged on the ninth day of admission to the ICU. The determination of metformin levels was 70.40 mg/l at plasma level and 53.10 mg/l at erythrocyte level.

