A 54-year-old woman with long-standing type 2 diabetes and microalbuminuria (urinary albumin-creatinine ratio 4.5 mg/mmol) has blood pressure 132/82 mmHg and eGFR 70 mL/min/1.73 m². She is not currently on an ACE inhibitor or ARB. According to Australian diabetes management guidance, what is the most appropriate intervention regarding her kidney risk?