Managing a patient with type 1 diabetes mellitus can be challenging to the inpatient medical team. These patients require a continuous supply of exogenous insulin, and the omission of even a single dose can result in severe hyperglycemia and diabetic ketoacidosis. This article aims to equip the inpatient medical team with the knowledge and expertise required to care for these patients in the hospital, including transitioning from home to hospital, transitioning from the intravenous insulin infusion to the subcutaneous route, subcutaneous insulin dosing including the insulin pump, and transitioning back to home.