Hezekiah Smith, a 55-year-old male, presents with a history of increasing fatigue, excessive thirst, frequent urination, and blurred vision over the past few months. He has a family history of type 2 diabetes. Physical examination reveals obesity, otherwise normal. Laboratory tests reveal a fasting blood glucose level of 159 mg/dL and a hemoglobin A1c level of 8.9%. He takes hydrochlorothiazide for hypertension. Which of the following is the drug of choice for initial treatment in this patient?
