Metformin-associated risk of acute dialysis in patients with type 2 diabetes: a nationwide cohort study

Recent guidelines governing anti-diabetic medications increasingly advocate metformin as first-line therapy in all patients with type 2 diabetes. However, metformin could be associated with increased risk of acute kidney injury (AKI), acute dialysis, and lactate acidosis in marginal patients. In a retrospective nationwide cohort study, a total of 168,443 drug-naïve patients with type 2 diabetes ≥50 years initiating treatment with either metformin or sulphonyl in Denmark between 2000 and 2012 were included (70.7% initiated treatment with metformin), and one-year risk of acute dialysis was calculated based on g-standardization of cause-specific Cox regression models for acute dialysis, end-stage renal disease, and death. One-year risks of acute dialysis were 92.4 per 100,000 (95% CI 67.1 - 121.3) and 142.7 per 100,000 (95% CI 118.3 - 168.0), for sulphonylurea and metformin, respectively. The metformin-associated one-year risk of acute dialysis was increased by 50.3 per 100,000 (95% CI 7.9 - 88.6), corresponding to a risk ratio of 1.53 (95% CI 1.06 - 2.23), and a number needed to harm of 1988; thus providing evidence of potential concerns pertaining to the increasing use of metformin.