A 52-year-old man from Mumbai with a 10-year history of type 2 diabetes presents for routine follow-up. He is currently on metformin 1000 mg twice daily and has maintained reasonable glycaemic control (HbA1c 7.2%). On examination, BMI is 28 kg/m², blood pressure 138/88 mmHg. Recent laboratory results: fasting glucose 128 mg/dL, serum creatinine 1.1 mg/dL (eGFR 65 mL/min/1.73 m²), urine albumin-to-creatinine ratio (UACR) 45 mg/g (indicating early diabetic nephropathy). He has no history of cardiovascular disease. Which of the following is the most appropriate next step in management?