A 48-year-old overweight woman is newly diagnosed with type 2 diabetes after an HbA1c of 64 mmol/mol (8.0%). She has no symptoms of hyperglycaemia, an estimated glomerular filtration rate of 80 mL/min/1.73 m² and no contraindications to any glucose-lowering medications. Lifestyle advice has been given. According to Australian guidelines, what is the most appropriate initial pharmacological treatment?