A 52-year-old man with hypertension and type 2 diabetes mellitus presents with a BP of 158/96 mmHg despite being on amlodipine 5 mg daily for 3 months. His serum creatinine is 1.2 mg/dL (eGFR 65 mL/min/1.73 m²) and urinalysis shows 2+ proteinuria. What is the most appropriate next step in management?

Explanation

## Clinical Context This patient has uncontrolled hypertension with evidence of diabetic nephropathy (proteinuria and mild renal impairment). The goal BP in diabetic patients with albuminuria is <130/80 mmHg per current guidelines. ## Why ACE Inhibitor Is the Best Choice **Key Point:** ACE inhibitors (and ARBs) are the first-line agents to add in hypertensive diabetic patients with albuminuria or renal disease, regardless of BP level, because they provide renal protection independent of BP lowering. **High-Yield:** In diabetic nephropathy: - ACE inhibitors reduce intraglomerular pressure by dilating the efferent arteriole - They reduce proteinuria and slow progression of renal disease - They are cardioprotective (reduce LV hypertrophy) - They are indicated even if BP is controlled, if proteinuria is present **Clinical Pearl:** The presence of proteinuria in a diabetic patient mandates ACE inhibitor or ARB therapy as part of the antihypertensive regimen. This is a fundamental principle in diabetic renal protection. ## Mechanism of Renal Protection ```mermaid flowchart TD A[Hypertension + Diabetes]:::outcome --> B[Glomerular hyperfiltration]:::outcome B --> C[Efferent arteriole vasoconstriction]:::outcome C --> D[Increased glomerular pressure]:::outcome D --> E[Proteinuria & GFR decline]:::urgent E --> F{ACE Inhibitor?}:::decision F -->|Yes| G[Efferent vasodilation]:::action F -->|No| H[Progressive renal disease]:::urgent G --> I[Reduced intraglomerular pressure]:::action I --> J[Proteinuria reduction & renal preservation]:::outcome ``` ## Dosing and Monitoring - Start lisinopril 10 mg daily (or enalapril 10 mg daily) - Monitor serum creatinine and K⁺ at 1–2 weeks and 4–6 weeks - A rise in creatinine ≤30% is acceptable; >30% warrants dose adjustment or discontinuation - Target BP: <130/80 mmHg in diabetics ## Why Not Other Options? - **Increasing amlodipine alone:** Calcium channel blockers do not provide renal protection in diabetic nephropathy; they are good BP-lowering agents but lack the glomerular-protective effect - **Beta-blockers:** Not first-line in diabetics (worsen glucose control, mask hypoglycemia); no specific renal protective effect in this context - **Thiazide diuretics:** Can worsen glucose metabolism and electrolytes; not preferred as add-on in diabetic patients with renal impairment [cite:Harrison 21e Ch 297]