Objective: We aim to evaluate how metformin affects the kidney disease progression in type 2 diabetes mellitus (T2DM) patients for 5 years follow-up using real-world evidence based on OMOP (Observational Medical Outcomes Partnership) CDM (Common Data Model). Methods: Initial target cohort was defined as people over 30-year-old were having the following conditions: diagnosed with T2DM or HbA1C ≥ 6.5% from CDM data (February 2011 to August 2018) in the Pusan National University Hospital. Estimated glomerular filtration rate (eGFR) ≥ 60 (mL/min/1.73m2) with metformin treatment for all days of the events were included. Type 1 DM and cancer patients were excluded as well as pregnant patients. The outcomes were subgrouped in terms of eGFR (< 45, and < 30, respectively) considering hemodialysis and peritoneal dialysis to evaluate the kidney function. We performed incidence rate analysis and cox proportional ratio with propensity score-matching. Results: Initial cohort treated with metformin was 5,963 with inclusion and exclusion criteria and comparator cohort without metformin treatment was 12,754. The incidence rate per 1,000 years for the outcomes: hemodialysis and peritoneal dialysis or (1) eGFR < 45 was 31.1 for metformin-treated and 36.5 for without metformin-treated, (OR: 0.85) (2) eGFR < 30 was 14.4 and 20.7 (OR: 0.700), (3) eGFR < 15 was 5.9 and 9.9 (OR: 0.60). The corresponding hazard ratios comparing metformintreated vs. no-metformin were not significantly different for all three outcomes; 1.16 (95% CI: 0.83, 1.63, P = 0.39) for eGFR < 45; 1.26 (95% CI: 0.76, 2.10, P = 0.37) for eGFR < 30, 1.09 (95% CI: 0.48, 2.51, P = 0.83) for eGFR < 15. Conclusion: Metformin did not differ in hazards of kidney disease progression for patients with T2DM. Further studies using the OMOP CDM collaborative network were needed to validate this result.