A 48-year-old man with obesity (BMI 32 kg/m²) is newly diagnosed with type 2 diabetes after A1C 8.2 percent. His eGFR is 90 mL/min/1.73 m², and liver enzymes are normal. He has implemented diet and exercise changes for 3 months with minimal improvement in fasting glucose. According to Diabetes Canada, which pharmacologic agent should be initiated first line in most people in this situation?