A 50-year-old woman is 5 ft 7 in tall and weighs 185 lb. There is a family history of diabetes mellitus. Fasting blood glucose (FBG) is 160 mg/dL and 155 mg/dL on two occasions. HgA1c is 7.9%. You educate the patient on medical nutrition therapy. She returns for reevaluation in 8 weeks. She states she has followed diet and exercise recommendations, but her FBG remains between 140 and 150 and HgA1C is 7.7%. She is asymptomatic, and physical examination shows no abnormalities. Which of the following is the treatment of choice?

The classification of diabetes mellitus has changed to emphasize the process that leads to hyperglycemia. Type 2 DM is a group of heterogeneous disorders characterized by insulin resistance, impaired secretion of insulin, and increased glucose production. In this type 2 patient, the first intervention, medical nutrition therapy, failed to achieve the goal HgA1c of less than 7.0%. Medical nutrition therapy (MNT) is a term now used to describe the best possible coordination of calorie intake, weight loss, and exercise. It emphasizes modification of risk factors for hypertension and hyperlipidemia, not just weight loss and calorie restriction. This was appropriately instituted in the question. Blood glucose control should be evaluated after 4 to 6 weeks and additional therapy should be added if the goal has not been reached. Metformin is considered first-line therapy in that it promotes mild weight loss, has known efficacy and side-effect profile, and is available as a generic with very low cost. Thiazolidinediones ("glitazones"), DPP-4 inhibitors, GLP-1 agonists, sulfonylureas, and insulin are all considered second-line or add-on therapy for most patients with type 2 DM.