Ancient herbal formula put to the test against diabetic kidney disease

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: 1. Age \>= 18 years. 2. Meets the diagnostic criteria for Type 2 diabetic nephropathy, defined as: 1. Confirmed diagnosis of Type 2 diabetes mellitus; AND 2. At least one of the following: urinary albumin-to-creatinine ratio (UACR) \>= 30 mg/g, or eGFR \< 60 mL/min/1.73m\^2, confirmed by repeat testing (interval \>= 3 months), after excluding transient factors such as acute kidney injury, dehydration, infection, or heart failure; OR 3. Renal biopsy confirmed as isolated diabetic nephropathy; AND 4. Exclusion of other primary or secondary kidney diseases. 3. 24-hour urinary protein excretion \>= 0.5 g and \< 3.5 g. 4. Estimated glomerular filtration rate (eGFR) \>= 45 mL/min/1.73m\^2. 5. On a stable dose of ACE inhibitor (ACEI) or Angiotensin II receptor blocker (ARB) therapy for at least 8 weeks prior to enrollment. If SGLT2 inhibitors, mineralocorticoid receptor antagonists (MRA), or GLP-1 receptor agonists are being used, the dose must have been stable for at least 4 weeks prior to enrollment and remain unchanged during the study period. Patients not currently using these agents must not initiate them during the study. 6. Signed informed consent form. Exclusion Criteria: 1. Type 1 diabetes mellitus or other types of diabetes mellitus (e.g., secondary diabetes, maturity-onset diabetes of the young). 2. Coexisting systemic autoimmune or immune-mediated disease where the clinical assessment suggests a non-diabetic nephropathy etiology. 3. Decline in eGFR of \> 30% within the past 3 months. 4. Persistent serum potassium \> 5.5 mmol/L. 5. Diagnosis of hemorrhagic cardiovascular or cerebrovascular disease within the past 3 months. 6. Known allergy or hypersensitivity to any component of Naoxintong Capsule or placebo; pregnant or lactating women. 7. Participation in another drug or medical device clinical trial within the past 6 months. 8. Any other condition that, in the investigator's judgment, renders the patient unsuitable for participation in the clinical trial (e.g., severe hepatic dysfunction, life expectancy \< 1 year).