A 45-year-old male presents with mild xerostomia, polydipsia for 2 months, accompanied by mild polyuria and markedly increased appetite. Height: 175 cm, weight: 85 kg. Fasting blood glucose (FBG): 8.7 mmol/L, 2-hour postprandial blood glucose (2hPPG): 13.1 mmol/L. What is the best treatment option for this diabetes mellitus (DM) patient?