This is a single-arm prospective clinical study conducted at The Fourth Affiliated Hospital of Zhejiang University School of Medicine. Previous basic research has found that patients with type 2 diabetic nephropathy have higher blood lead levels than ordinary people, and lead accumulation may accelerate kidney function decline. A total of 42 eligible participants will be enrolled, who are diagnosed with type 2 diabetic nephropathy, have baseline blood lead ≥5 µg/dl, CKD stage ≤3 and 24-hour urinary protein <8 g. All subjects will receive oral dimercaptosuccinic acid (DMSA) capsules for lead removal according to standardized treatment courses for up to 3 months. During treatment, blood lead, urine lead, renal function and other indicators will be tested monthly. After the 3-month intervention, all participants will be followed up for 12 months, with relevant laboratory examinations conducted every 3 months to observe changes in renal function. The main goal of this study is to evaluate whether oral lead chelation therapy can slow the progression of kidney damage in patients with high lead burden and type 2 diabetic nephropathy, and provide clinical evidence for the intervention of lead-induced kidney injury in diabetic populations. Patients with hypertension, hyperlipidemia, autoimmune diseases, malignant tumor history, previous occupational lead exposure or drug allergies will not be enrolled. No healthy volunteers will be recruited, and individual raw patient data will not be shared externally after the study.

Inclusion Criteria:

1. Diagnosed with type 2 diabetic nephropathy;
2. Baseline blood lead level ≥ 5 μg/dL;
3. Chronic kidney disease stage ≤ 3;
4. 24-hour urinary protein < 8 g;
5. Age ≥ 18 years;
6. Able to voluntarily sign a written informed consent form.

Exclusion Criteria:

1. Combined hypertension or hyperlipidemia;
2. Confirmed history of autoimmune diseases;
3. Personal history of malignant tumors;
4. Reversible renal insufficiency (malignant hypertension, active urinary tract infection, recent use of nephrotoxic drugs);
5. Previous occupational lead exposure history;
6. Known drug allergy to dimercaptosuccinic acid;
7. Unable to complete regular follow-up visits.