Background: Sensor-integrated pump systems with low-glucose suspend (also known as threshold suspend) functions have markedly transformed the management of type 1 diabetes, but most studies to date have excluded patients at high risk of hypoglycemia. The SMILE study is investigating the efficacy of the MiniMed™ 640G insulin pump with the SmartGuard™ predictive low-glucose management (PLGM) feature in the prevention of hypoglycemia in adults with type 1 diabetes, who are at high risk of hypoglycemia. Methods: SMILE is a prospective, randomized, open-label, controlled trial being undertaken in four European countries and Canada. Following a 2-week run-in phase, eligible participants will be randomized to use either the MiniMed 640G system with continuous glucose monitoring (CGM) and the SmartGuard PLGM feature on continuously for 24 weeks (treatment arm), or the MiniMed 640G without CGM and with blinded continuous glucose measurements between weeks 10-12, 16-18, and 22-24 (control arm). The primary endpoint is the mean number of hypoglycemic events, defined as sensor glucose ≤55 mg/dL (≤3.0 mmol/L) for >20 consecutive minutes. Secondary endpoints include various glycemic indices in the hypoglycemic and hyperglycemic ranges, as well as glycated hemoglobin. Data on patient-reported outcomes such as hypoglycemia awareness and treatment satisfaction will also be collected. Conclusions: It is anticipated that the SMILE study will provide important insights into the effectiveness of SmartGuard technology in adult patients with type 1 diabetes. © 2018, Mary Ann Liebert, Inc.