Neonatal diabetes mellitus (NDM) is a rare metabolic disorder that is mainly present in the first 6 months of life and necessitates insulin treatment. Sensor-augmented pump (SAP) therapy has been widely used in children with type 1 diabetes mellitus, but its use in patients with NDM is limited. We report three patients with NDM who received SAP therapy using the MiniMed™ 640G system starting in the neonatal period. Two patients were treated for 3 months, and one patient continued treatment up to an age of 22 mo. The MiniMed 640G system can automatically suspend insulin delivery (SmartGuard™ Technology) to avoid hypoglycemia when the sensor glucose level is predicted to approach the predefined threshold. We suggest that SmartGuard Technology is particularly useful for infants in whom hypoglycemia cannot be identified. The MiniMed 640G system automatically records the trends of sensor glucose levels and the total daily dose of insulin, which can make the management more accurate and reduce the family's effort. SAP therapy for patients with NDM automatically prevents severe hypoglycemia and is useful for long-term management; however, attention should be paid to its application.