A 58-year-old man with a 10-year history of type 2 diabetes mellitus presents to the nephrology clinic. His blood pressure is 148/92 mmHg despite being on amlodipine 5 mg daily. Serum creatinine is 2.8 mg/dL (eGFR 24 mL/min/1.73m²), and urine dipstick shows 3+ proteinuria. Urinary albumin-to-creatinine ratio (UACR) is 450 mg/g. He denies edema or dyspnea. What is the most appropriate next step in management to slow progression of his chronic kidney disease?

Explanation

## Rationale for CKD Management in Diabetic Nephropathy **Key Point:** ACE inhibitors and ARBs are the cornerstone of renoprotective therapy in diabetic CKD, regardless of blood pressure, because they reduce intraglomerular pressure and proteinuria. **High-Yield:** The KDIGO 2021 guidelines recommend: - ACE-I or ARB as first-line agents in all diabetic patients with CKD and albuminuria - Blood pressure target: <130/80 mmHg (more stringent than non-diabetic CKD) - These agents slow GFR decline by ~20–30% independent of blood pressure lowering **Clinical Pearl:** This patient has stage 3b CKD (eGFR 24) with significant proteinuria (UACR 450 mg/g, indicating overt diabetic nephropathy). The combination of diabetes + proteinuria + hypertension creates a "triple threat" to the kidney. ACE-I/ARB therapy is evidence-based and delays progression to ESRD. **Mechanism:** ACE-I/ARB dilate the efferent arteriole preferentially, reducing glomerular capillary pressure (P~GC~) and proteinuria, while preserving renal perfusion pressure. ### Why This Patient Needs Intensification - Current BP 148/92 is above target (<130/80) - UACR 450 indicates overt albuminuria despite monotherapy - eGFR 24 is stage 3b — intervention now prevents rapid decline [cite:Harrison 21e Ch 297]