A 75-year-old man with long-standing hypertension and type 2 diabetes presents with rising creatinine. His eGFR has fallen from 65 to 40 mL/min/1.73 m² over 2 years, and urine albumin:creatinine ratio is 45 mg/mmol. Blood pressure is 136/78 mmHg on an ACE inhibitor and thiazide diuretic. According to CKD management guidance, which intervention has the strongest evidence to slow his renal disease progression?