The purpose of this study is to investigate the effect of topiroxostat on urinary albumin excretion and the safety in patients with early stage diabetic nephropathy and hyperuricemia with or without gout. Participants are randomized to placebo (n=20) or topiroxostat (n=40) for 28 weeks. The investigational drugs for this study are supplied by FUJI YAKUHIN CO., LTD.

Inclusion Criteria:

• Diabetes patients
• Clinically or pathologically diagnosed diabetic nephropathy
• Hyperuricemic or gout patients
• Estimated glomerular filtration rate (eGFR) >= 30 mL/min/1.73m^2 and urine albumin creatinine ratio (UACR) greater than or equal to 45 and less than 300 mg/g

Exclusion Criteria:

• Patient has known non-diabetic nephropathy (other than nephrosclerosis)