[Lactic acidosis associated with metformin: A case series from the Saint-Denis hospital]

Introduction: Metformin is a first line treatment for type II diabetes. Cases of metformin-associated lactic acidosis are regularly reported. A direct causal link between metformin overdose and lactic acidosis is not clearly established. The aim of this study is to describe cases of metformin-associated lactic acidosis, to assess their vital et renal prognosis, and to analyze the correlations between metforminemia, lactacidemia, pH and death.

Methods: Cases of metformin-associated lactic acidosis from a single hospital center in Saint-Denis, France, between 2010 and 2022 were analyzed. Inclusion criteria were patients aged 18 or older, treated with metformin, metabolic acidosis with a pH inferior to 7.35 and lactacidemia superior to 5mmol/l.

Results: Twenty-eight patients were included. Median age was 65 years old. Voluntary intoxication was present in 17% of cases. Metformin was contraindicated in 39% of cases. All patients presented with acute kidney injury at admission. Mortality rate was 7%. No factor was associated with death in the univariate analysis. Correlation between pH, lactacidemia, creatininemia and glycated hemoglobin was found. There was no correlation between metforminemia and lactacidemia.

Conclusion: Metformin-associated lactic acidosis is a rare complication. Its prognosis is inconstant, varying with the presence or absence of a severe disease causing the overdose. No association was found between clinical data, biological data and death.