Bicarbonate haemodialysis: an adequate treatment for lactic acidosis in diabetics treated by metformin.

Lactic acidosis in diabetics on metformin therapy is rare but still associated with poor prognosis. The authors report here five cases. Three patients were initially with a cardiovascular collapse and all had an acute renal failure. Sodium bicarbonate haemodialysis therapy led to a dramatic improvement. Consciousness and hemodynamic status recovered rapidly. Severe metabolic and blood gases derangements were also rapidly corrected. Plasma metformin removal, appreciated by repeated blood samplings in 3 cases, was satisfactory. All patients survived. However, blood metformin levels remained abnormally high at the end of the dialytic therapy. In conclusion, (1) bicarbonate dialysis is an adequate treatment of lactic acidosis observed in diabetic patients treated with metformin since it rapidly corrects the acid-base disorders and partially removes metformin; (2) the sole accumulation of metformin is not sufficient to explain lactic acidosis since this latter might be corrected in spite of persisting high levels of blood metformin.