Table 1 Inclusion and exclusion criteria

1. Men and women

1. Uncontrolled diabetes mellitus; HbA_1c: ≥8.0% (JDS) or ≥8.4% (NGSP)

2. Age ≥20 years at informed consent

2. Systolic blood pressure ≥160 mmHg or diastolic blood pressure ≥100 mmHg

3. Patients with hyperuricemia; serum uric acid: 7.1-10.0 mg/dL

3. ALT or AST: greater than twice the upper limit of institutional reference range

4. eGFR: 30–59 mL/min/1.73 m² (CKD stages 3a and 3b)

4. Change in serum creatinine level by more than 50% within 12 weeks before the confirmation of eligibility

5. No history of gout

5. Acute renal disease, nephrotic syndrome, other serious disease, dialysis, or renal transplantation

6. Written informed consent for study enrollment obtained from the patient

6. Complication or history of malignant tumor (not excluded from the study when the malignant tumor is not treated within 5 years and if there is no recurrence)

7. History of hypersensitivity to febuxostat

8. Intake of any one or more of the following drugs at the confirmation of eligibility: mercaptopurine hydrate, azathioprine, vidarabine, and didanosine

9. Intake of any one or more of the following urate-lowering drugs within 4 weeks before the confirmation of eligibility: allopurinol, benzbromarone, probenecid, bucolome, and febuxostat

10. Initiation of intake, dose modification, or discontinuation of intake of any one or more of the following drugs within 4 weeks before the confirmation of eligibility: losartan, fenofibrate, thiazide diuretics, and loop diuretics

11. Continuous intake of salicylic acid drugs, e.g., aspirin (the patient taking low-dose aspirin [≤324 mg/day] need not to be excluded from the study)

12. Hormone replacement therapy with estrogens

13. Pregnancy, nursing, or planed pregnancy during the study

14. Enrollment in other clinical trials within 24 weeks before providing informed consent

15. Ineligibility at the investigator’s discretion