Since metformin is safe and effective for glucose management in patients with type 2 diabetes and normal renal function, we propose its continuation during hospitalization. This study will include adult patients with type 2 diabetes currently treated with metformin alone or in combination with other anti-diabetic agents including low dose insulin. All subjects will have normal renal function (eGFR>60 ml/min) and no comorbidities that increase the risk for acidosis. This prospective, randomized controlled trial will compare metformin and sitagliptin (which cannot cause hypoglycemia) to usual insulin therapy, which is known to cause hypoglycemia. This study has possible implications for improving the safety of therapy for hospitalized patients with type 2 diabetes.