The authors present results of 31 patients treated with buformin who developed severe metabolic lactic acidosis (MLAc), probably caused by administration of this drug. They evaluate the risk of the undesirable effect of buformin (biguanides) used in the treatment of diabetes mellitus 2 in patients complications of disease. During the period 1989–1998 approximately 7 796 (6.8%) subjects in the region suffered from diabetes mellitus (type 2). 2 021 patients i.e. 1.76% were treated with biguanides. The most widely used biguanide at that time was buformin. In this study 31 patients, average age 69 years, were studied. 11 patients (35%) survived, 20 patients died (65%). The mean value of pH was 7.04 (SD 0.2), the serum lactate level was 13.90 (SD 6.07) mmol/l, BE was –20.4 (SD 8.65) mmol/l. According to the results 1.53 patients (on average) are threatened with development of metabolic lactate acidosis per year per 1 000 patients treated with buformin (biguanides). Two of three patients, who develop biguanide-induced MLAc, die. The authors evaluate problems with the therapy and high mortality rate of patients with severe lactate acidosis caused by biguanide administration. They assess particular signs, associated with the mentioned disorder, they search for causes where the clinical and laboratory picture is not characteristic and therefore not diagnosed.

        Key words: lactic acidosis, biguanides, buformin, diabetes mellitus 2.