A 58-year-old woman with type 2 diabetes for 10 years and hypertension develops new persistent microalbuminuria (ACR 5 mg/mmol) with eGFR 75 mL/min/1.73 m². She is on metformin and a calcium channel blocker; blood pressure averages 136/84 mmHg. According to Diabetes Canada and kidney guidance, what is the best next step?