Effect of metformin on kidney function in patients with type 2 diabetes mellitus and moderate chronic kidney disease

Background: Impaired renal function can lead to the accumulation of metformin, and elevated concentrations of metformin have been associated with lactic acidosis. The aim of this study was to evaluate the effect of continuous metformin treatment in patients with type 2 diabetes mellitus (DM) and moderate chronic kidney disease (CKD) (estimated glomerular filtration rate (eGFR) 30-0 ml/min/1.73 m(2)) on renal function. Methods: A total of the 616 patients were enrolled from the research database of Kaohsiung Medical University Hospital from January 1 to 2009 and December 31, 2013. The patients were divided into two groups: those who continued metformin treatment (continuation group; n = 484), and those who discontinued metformin treatment for at least 100 days (interruption group; n = 132). Results: The slope of eGFR in the metformin interruption group was statistically lower than that in the metformin continuation group (0.75 +/- 0.76 vs. -1.32 +/- 0.24 mL/min/1.73 m(2)/year, p = 0.0007). After adjusting for baseline covariates in the multivariate linear regression analysis, the continuation of metformin (unstandardized coefficient beta, -2.072; 95% confidence interval, -3.268- -0.876) was a risk factor for the patients with DM and moderate CKD. Conclusions: Metformin may have an adverse effect on renal function in patients with type 2 DM and moderate CKD.