Continuous subcutaneous insulin infusion (CSII) via insulin pump delivers rapid-acting insulin analogs to mimic physiologic insulin secretion. The basal rate provides continuous low-dose insulin to suppress hepatic glucose production between meals and overnight, while patient-programmed bolus doses cover carbohydrate intake and correct hyperglycemia. Modern pumps may integrate with continuous glucose monitors (CGM) in sensor-augmented pump therapy or hybrid closed-loop systems. Pump therapy reduces A1C and glycemic variability compared to multiple daily injections (MDI) but carries unique risks: site failure, pump malfunction, and rapid progression to DKA because no long-acting insulin depot exists. The nurse must manage pump therapy during hospitalization, troubleshoot device issues, and implement sick day protocols.