Metformin-associated lactic acidosis

Introduction Metformin is the first choice drug in type II diabetes. This drug has a renal excretion and its use requires caution in a setting of glomerular filtration rate reduction; an accumulation can be associated with a lactic acidosis, complication burden with a high rate mortality. Methods In a user base of 390.000 people we reviewed all the cases of metformin-associated lactic acidosis treated at the First Aid in a 15 months period; we considered the patients characteristics, their risk factors and the outcome. Results We observed 11 cases (incidence 60/year/100.000 patients). 10 had an acute renal failure due to dehydration. None had absolute contraindications to metformin, but most of the patients had at least one risk factor for acute kidney injury. 10 patients had been treated with hemodialysis. The total mortality rate was 36%. Conclusions In our experience we found a higher incidence compared to literature, probably because of the widespread use of this drug in more and more fragile patients. We confirm the need of a strict adherence to prescription with a specific attention, not only to renal function, but also to the concomitant presence of risk factors (age over 80, use of Ace-inhibitors, angiotensin receptor blockers and diuretics). We draw the attention to the importance of acute clinical events and we reaffirm the need of an adequate education of the patient and his relatives for a better management of the acute event.