A 45-year-old woman with type 2 diabetes mellitus managed with metformin and lifestyle measures attends for review. Her HbA1c is 8.5% (69 mmol/mol) despite adherence. She has an eGFR of 65 mL/min/1.73 m2 and no albuminuria. According to current Australian primary care guidance, what is the most appropriate next pharmacological step?