A comprehensive, collaborative approach is necessary for optimal treatment of patients with type 2 diabetes mellitus. Treatment guidelines focus on nutrition, exercise, and pharmacologic therapies to prevent and manage complications. Patients with prediabetes or new-onset diabetes should receive individualized medical nutrition therapy, preferably from a registered dietitian, as needed to achieve treatment goals. Patients should be treated initially with metformin because it is the only medication shown in randomized controlled trials to reduce mortality and complications. Additional medications such as sulfonylureas, dipeptidyl-peptidase-4 inhibitors, thiazolidinediones, and glucagon-like peptide-1 receptor agonists should be added as needed in a patient-centered fashion. However, there is no evidence that any of these medications reduce the risk of diabetes-related complications, cardiovascular mortality, or all-cause mortality. There is insufficient evidence on which combination of hypoglycemic agents best improves health outcomes before escalating to insulin therapy. The American Diabetes Association recommends an A1C goal of less than 7% for many nonpregnant adults, with the option of a less stringent goal of less than 8% for patients with short life expectancy, cardiovascular risk factors, or long-standing diabetes. Randomized trials in middle-aged patients with cardiovascular risk factors have shown no mortality benefit and in some cases increased mortality with more stringent A1C targets.