This multicenter, randomized, open-label, controlled study will assess the efficacy of the SGLT2 inhibitor tofogliflozin on Urine Albumin-to-Creatinine Ratio (UACR) compared to metformin in patients with type 2 diabetes with chronic kidney disease (CKD).

Eligible participants will be randomly assigned (1:1) to tofogliflozin or metformin with stratification based on UACR (<300 mg/gCr，≧300mg/gCr), an estimated glomerular filtration rate (eGFR) (<60mL/min/1.73m2, ≧60 mL/min/1.73m2), and age (<65 years old, ≧65 years old). The primary end point is change in urine albumin-to-creatinine ratio (UACR) from baseline after 52 weeks treatment. Changes in eGFR, HbA1c, body weight, systolic blood pressure, diastolic blood pressure, total serum proteins, serum albumin, uric acid, hematocrit, hemoglobin, red blood cell count, pulse rate, triglyceride, low-density lipoprotein, high-density lipoprotein and albuminuria class transition rate will also be evaluated.

Inclusion Criteria:

• Type 2 diabetic patients
• Patients aged 20 years or older at the time of obtaining consent
• Patients with HbA1c 6.5 or more and 9.0% or less within 13 weeks before obtaining consent (evaluated by test values after 4 weeks or more without taking SGLT2 inhibitor / metformin)
• Patients who have been judged by their doctor to need a diabetic drug when they are first seen, or who have already taken a diabetic drug and have decided that it is necessary to add one diabetic drug.
• Patients who have been receiving RAS inhibitors (ARB, ARNI, ACE inhibitors, direct renin inhibitors) for 4 weeks or longer
• Patients with eGFR of 30 or more (mL / min / 1.73m2) within 13 weeks before obtaining consent (evaluated by test values after 4 weeks or more without taking SGLT2 inhibitor / metformin)
• Patients with urinary albumin / creatinine ratio (UACR) of 30 or more and less than 2000 (mg / gCr) (4 weeks or more without taking SGLT2 inhibitor / metformin) within 13 weeks before obtaining consent Evaluate by inspection value)
• Patients for whom written consent was obtained based on the patient's free will after receiving sufficient explanation for participation in this study

Exclusion Criteria:

• Patients receiving treatment with SGLT2 inhibitor or metformin within 13 weeks before obtaining consent
• Dialysis patient
• Patients with a history of severe hypoglycemia
• Patients with hypersensitivity to SGLT2 inhibitor or metformin
• Pregnant women, lactating patients, and patients who wish to raise children
• Patients with BMI of 35 kg / m2 or more based on the latest measured values within 13 weeks before obtaining consent
• Patients who are contraindicated for the study drug
• Other patients who the attending physician deems inappropriate as a subject