Diabetic nephropathy is often a clinical diagnosis based on the persistence of an increased urinary albumin/creatinine ratio and/or a predicted decrease in glomerular filtration rate, with exclusion of other chronic kidney diseases. Pathologic diagnosis is the gold standard for diabetic nephropathy, and renal puncture pathology is feasible when the etiology is difficult to identify, but routine renal puncture biopsy is not recommended for diabetic patients. After the diagnosis of diabetic nephropathy is established, the severity of chronic kidney disease should be further determined based on the estimated glomerular filtration rate. Diabetic nephropathy is one of the chronic complications of diabetes mellitus. Patients with diabetic nephropathy should standardize their diagnosis and treatment under the guidance of professional doctors to avoid delays and serious consequences.