In a patient with hypertension and diabetes mellitus, which drug class is first-line to protect renal function?

• A. ACE inhibitors
• B. Calcium channel blockers
• C. Thiazide diuretics
• D. Beta blockers

Answer: (A)

ACE inhibitors are preferred in patients with both hypertension and diabetes because they protect kidney function by directly reducing pressure inside the glomeruli. They block the formation of angiotensin II, which normally constricts the efferent arteriole. When this arteriolar constriction is reduced, the efferent arteriole dilates, lowering intraglomerular pressure, decreasing protein leakage into the urine (proteinuria), and slowing the progression of diabetic nephropathy. This renoprotective effect happens in addition to lowering blood pressure and provides cardiovascular benefits, making them the first-line choice for preserving renal function in diabetes. If ACE inhibitors aren’t tolerated, ARBs are a common alternative. The other drug classes lower blood pressure but don’t offer the same direct kidney protection, so they’re not as ideal for safeguarding renal function in this scenario.