A 58-year-old man with a 10-year history of Type 2 diabetes presents for routine follow-up. His HbA₁c is 8.2%, fasting glucose 156 mg/dL, and eGFR 62 mL/min/1.73m². He has hypertension and mild albuminuria. He is currently on metformin monotherapy. Which agent should be added as second-line therapy to provide cardio-renal protection?