[A clinical case of lactic acidosis development in a diabetic patient taking metformin]

Metformin is a biguanide. Due to its effects in decreasing the hepatic production of glucose and in increasing insulin sensitivity in peripheral tissues, such as adipose tissue and skeletal muscle, the agent is used in metabolic syndrome and type 2 diabetes mellitus and, in which insulin resistance is especially pronounced. Eighty-one-year old male patient was admitted to the emergency unit with sudden vertigo, tiredness, dyspnea, cyanosis, and lethargy. He had had type 2 diabetes mellitus for 10 years and was taking glargin 12 U/kg once daily and metformin (glucophage) 850 mg thrice daily. The patient showed no cooperation and orientation. Metabolic acidosis, hypoxemia, and hypercapnea were detected in arterial blood gases (ABG). The patient was transferred to an intensive care unit of the hospital; endotracheal intubation was applied and mechanic ventilation was started. On the following day, his ABG got better; he was disconnected and weaning was applied. Lung X-ray study revealed no signs of pneumonia or pulmonary edema. On the same day, extubation was ended and O2 was given by mask at a rate of 4 L/min. After the patient's vital signs, blood sugar, and lactate levels were stabilized; his treatment regimen was arranged again and the patient was discharged on day 4 of his admission. Dyspnea, acidosis, and hypoxia seen in the patient were thought to be due to lactic acidosis which may rarely occur when metformin is used.