Renal protective effect of metformin in type 2 diabetes patients

Abstract Background Inhibiting the development and progression of diabetic kidney disease (DKD) is an important issue, but the renoprotective effect of metformin is still controversial. Objective To assess the renoprotective effect of metformin in patients with type 2 diabetes. Methods This retrospective observational multicenter cohort study included 316 693 patients with type 2 diabetes from 7 hospitals. After matching for age, gender, medical year, baseline estimated glomerular filtration rate (eGFR), urine protein (dipstick), glycated hemoglobin (HbA1c) and propensity score; a total of 13 096 metformin and 13 096 non-metformin patients were included. The main results were doubling of serum creatinine, eGFR ≤ 15 mL/min/1.73 m2 and end-stage kidney disease (ESKD). Results After conducting a multivariable logistic regression analysis on the variables, the metformin group was revealed to have better renal outcomes than the non-metformin group, including a lower incidence of doubling of serum creatinine (hazard ratio [HR], 0.71; 95% CI, 0.65-0.77), eGFR ≤ 15 mL/min/1.73 m2 (HR 0.61; 95% CI, 0.53-0.71), and ESKD (HR 0.55; 95% CI, 0.47-0.66). The subgroup analyses revealed a consistent renoprotective effect across patients with various renal functions. Furthermore, when considering factors such as age, sex, comorbidities, and medications in subgroup analyses, it consistently showed that the metformin group experienced a slower deterioration in renal function across nearly all patient subgroups. Conclusion Metformin decreased the risk of renal function deterioration.