Metformin-induced lactacidosis

History and admission findings: A 62-year-old woman had been found unconsci ous on her bed. She had to be resuscitated several times in the ambulance o n the way to hospital. On admission her pupils were dilated and fixed, the cardiovascular system was unstable. Her rectal temperature was 28 degrees C . She was a diabetic being treated with metformin and glimepiride and was i n incipient renal failure (serum creatinine 1.5 mg/dl). She was also in hea rt failure due to coronary heart disease and was in a debilitated state. Investigations: She had marked lactacidosis (lactate 45.3 mmol/l; pH 6.6). Toxicological screening tests were negative. Treatment and course: In the absence of a history she was at first treated symptomatically. Conventional management of the lactacidosis neither correc ted the acidosis nor stabilized the circulatory system. Continuous veno-ven ous haemodialysis with bicarbonate-buffered solutions succeeded in reducing the need for catecholamines. Neurological examination was supplemented by recording acoustic and sensory evoked potentials. Suspected metformin-induc ed lactacidosis was confirmed by appropriate tests. Three weeks after admis sion she was well enough to be transferred to a normal medical ward and ult imately discharged without further complications. Conclusion: Metformin should only be prescribed if the contraindications, i n particular renal failure are carefully monitored. Severe lactacidosis sho uld be treated early with continuous veno-venous haemodialysis with bicarbo nate-buffered substituting fluids. The good neurological results in this ca se are probably largely due to the marked hypothermia.