In Clinic Evaluation of the PLGM Feature

A total of up to 95 subjects with type 1 diabetes (age 14-75 years old) will be enrolled at up to 8 investigational centers in order to reach a minimum of 60 subjects who will complete the study (N=minimum 40 adult subjects, 22-75 years old) and N=minimum 15 pediatric subjects (14-21 years old). Subjects will be evaluated in an in-clinic setting with induction of hypoglycemia by increasing their basal rate using a standardized titration tool referred to in protocol as rate of change basal increase algorithm (Buckingham, Diabetes Care 5, 2010). Total duration of frequent sample testing (FST) using Yellow Springs Instrument (YSI) may be up to 19 hours. Subjects will undergo in-clinic testing on Sensor Day 1. All subjects will undergo hypoglycemic induction at Visit 2 with target set to 65 mg/dL using the rate of change basal increase algorithm. Low Limit setting when PLGM ON is 65 mg/dL. The In-Clinic part of the study consists of hypoglycemic induction and an observation period. Hypoglycemic induction ends when one of the following 3 criteria is met, whichever comes first: 1. PLGM is activated 2. YSI glucose is less than or equal to 65 mg/dL, followed by the next YSI sample less than or equal to 65 mg/dL (2 contiguous YSI samples). 3. Neither condition for #1 or #2 has been met in 12 hours Observation with YSI ends when: 1. If PLGM is activated, observation with YSI frequent sample testing will include the Suspend period (30 minutes minimum to 2 hours maximum) and insulin resumption period (approximately 4 hours from the time insulin delivery resumes). This may include insulin re-suspension during this period. Maximum observation with YSI frequent sample testing should be no longer than 19 hours. 2. YSI glucose less than or equal to 65 mg/dL is followed by the next YSI sample less than or equal to 65 mg/dL (2 contiguous YSI samples). The subject will be rescued and YSI observation will end 3. Twelve hours have passed since the start of hypoglycemic induction without PLGM activation 4. See In-Clinic Stopping rules Enrollment for this study will proceed in phases. Phase 1 only allows enrollment of adult subjects (22-75 years). Subjects will wear pump system, as shown below: * One Study Pump * One GST-3C Transmitter * One Enlite 3 Sensor Progression to Phase 2 may occur after 10 adult subjects have completed Phase 1 and a Data Safety Monitoring Board (DSMB) has approved that it is safe to continue on to Phase 2. Phase 2 enrollment involves a minimum of 15 pediatric subjects (14-21). Subjects will wear the same pump system as shown for Phase 1. A total of up to 95 subjects will be enrolled at up to 10 investigational centers in order to reach a minimum of 60 subjects (N=minimum 40 adult subjects and N=minimum 15 pediatric subjects) who will complete the study. Considering around 15% screen failure rate and approximately 15% drop-out rate, a total of up to 95 subjects will be enrolled in order to have 60 subjects complete the study. 1. The investigational centers will be encouraged to include subjects of different ethnicities including Hispanic, Native American, and African-American 2. Subjects will be grouped into cohorts by Age The study is anticipated to last no longer than 12 months from investigational center initiation to completion of all data entry and monitoring procedures including final report. Subjects can expect to participate for approximately 2-3 weeks.