Acute kidney injury, plasma lactate concentrations and lactic acidosis in metformin users: A GoDarts study

Abstract

Aims: Metformin is renally excreted and has been associated with the development of lactic acidosis. Although current advice is to omit metformin during illnesses that may increase the risk of acute kidney injury (AKI), the evidence supporting this is lacking. We investigated the relationship between AKI, lactate concentrations and the risk of lactic acidosis in those exposed to metformin. Materials and Methods: We undertook a population-based case-control study of lactic acidosis in 1746 participants with Type 2 diabetes and 846 individuals without diabetes with clinically measured lactates with and without AKI between 1994 and 2014. AKI was stratified by severity according to “Kidney Disease: Improving Global Outcomes” guidelines. Mixed-effects logistic and linear regression were used to analyse lactic acidosis risk and lactate concentrations, respectively. Results: Eighty-two cases of lactic acidosis were identified. In Type 2 diabetes, those treated with metformin had a greater incidence of lactic acidosis [45.7 per 100 000 patient years; 95% confidence interval (CI) 35.9-58.3] compared to those not exposed to this drug (11.8 per 100 000 patient years; 95% CI 4.9-28.5). Lactate concentrations were 0.34 mmol/L higher in the metformin-exposed cohort (P