This study will test the hypothesis that a wearable automated bionic pancreas system that automatically delivers both insulin and glucagon can improved glycemic control vs. usual in the outpatient environment.
The study population will be volunteers with type 1 diabetes who are 21 years of age or older. The setting will be an outpatient environment in a three square-mile area on the Boston Peninsula (see Appendix A). Volunteers will stay in a hotel adjacent to the MGH campus at night and will have free activity during the day within the specified geographic area. They will determine the timing and nature of their meals from local restaurants, with food brought from home, or food kept in their hotel room, which will have a small refrigerator. They will have the opportunity to exercise as they wish in their choice of two gyms. There will be minimal scheduling constraints, limited only by an 11:00 PM curfew and morning departure time from the hotel of no earlier than 7:00 AM. They will be able to work if they wish as long as that can be done within the geographical constraints (e.g. if they work in the downtown Boston area or can "work from home" or have meetings at a conference room in the hotel or at a restaurant). During the entire experiment they will be closely monitored by study staff (RN, NP, or MD) around the clock. They will remain within direct line of sight and no more than a short distance away from study staff during the daytime for safety. During the night they will be continuously monitored via BG telemetry from a nearby hotel room and study staff will be able to enter their rooms quickly, should that become necessary. During the night, when volunteers will remain in their rooms, one study staff member will monitor up to two volunteers at a time. Capillary BG will be tested every two hours during the day using a highly accurate, laboratory equivalent meter (HemoCue, selected for maximum data integrity) and venous BG will be tested every 30 minutes overnight using an autosampling device (GlucoScout). Continuous glucose monitoring (Dexcom G4) will be done throughout the study period. Photos and menu information, if available, will be documented for each meal and snack by the escort and estimates of carbohydrate intake will be estimated later from this information by a nutritionist. The type and level of activity being performed by the volunteers (e.g. lying, sitting, standing, walking, running) will be documented in 15 minute intervals by the study staff escort. Additional data will be collected using an accelerometer. During exercise, the type and duration of exercise, and, depending on the kind of activity, the heart rate (recorded using a Polar heart rate monitor) will be documented every 15 minutes and point-of-care blood glucose will be documented every 30 minutes.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
32
A computer algorithm will automatically deliver insulin lispro and glucagon based on the signal from a minimally invasive continuous glucose monitor.
Massachusetts General Hospital
Boston, Massachusetts, United States
Average Blood Glucose (Co-primary Outcome)
Average blood glucose during the closed-loop control period as determined from HemoCue capillary measurements (daytime+nightime) and GlucoScout venous measurements (nighttime).
Time frame: 5 days of closed-loop control
Percentage of Time Blood Glucose Values Less Than 70 mg/dl (Co-primary Outcome)
Percentage of time blood glucose values during the closed-loop control period less than 70 mg/dl determined from HemoCue capillary measurements (daytime) and GlucoScout venous measurements (nighttime) during day 1-5. During usual care (open loop), blood sugars were not checked through GlucoScout or HemoCue (as per usual care fashion) and so were not compared to bionic pancreas (closed loop) arm
Time frame: 5 days
Average BG During the Closed-loop Control Period as Determined From All HemoCue Measurements Taken During the Daytime and All Scheduled GlucoScout Measurements During the Nighttime.
During usual care (open loop), blood sugars were not checked through GlucoScout or HemoCue (as per usual care fashion) and so were not compared to bionic pancreas (closed loop) arm
Time frame: 5 days
Percentage of the Subset of BG Values Less Than 70 mg/dl as Determined From All All HemoCue Measurements Taken During the Daytime and Scheduled GlucoScout Measurements Taken During the Nighttime.
Time frame: 5 days
Difference in the Average BG Between the Closed-loop Control Period and the Usual Care Period.
Time frame: 5 days
Difference in the Percentage of the Above Subset of BG Values Between the Closed-loop Control and Usual Care Periods Less Than 70 mg/dl.
Time frame: 5 days
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Percentage of Subjects With Mean BG < 154 mg/dl.
This outcome measure was only assessed for the closed loop control period, and was not assessed during the usual care arm.
Time frame: 5 days
Difference in the Percentage of Subjects With Mean BG < 154 mg/dl During the Closed-loop Period vs. the Usual Care Period.
Time frame: 5 days
Number of Hypoglycemic Events as Determined From GlucoScout and HemoCue Measurements.
Time frame: 5 days
Nadir BG During Exercise.
Time frame: 5 days
Correlation Between Exercise Intensity and Likelihood of a Hypoglycemic Event
Time frame: 5 days
Average BG During the Closed-loop Control Period as Determined From All GlucoScout Measurements Taken During the Nighttime Monitoring.
This outcome measure was only assessed for the closed loop control period, and was not assessed during the usual care arm.
Time frame: 5 days
Fraction of Time Spent Within Each of the Following Glucose Ranges as Determined From All GlucoScout and HemoCue Measurements.
Measurements adjusted for the frequency of measurement (i.e. modeled so that more frequent measurements at the time of hypoglycemia and exercise will not skew the mean): \< 70 mg/dl,70-120 mg/dl,70-180 mg/dl, \>180 mg/dl, \>250 mg/dl
Time frame: 5 Days
Difference of Outcome Measures on Days 1-2 vs. on Remaining Days (Days 3-5) During the Closed-loop Period.
Time frame: 5 Days
Mean BG During Exercise.
Time frame: 5 days
Number of Hypoglycemic Episodes During Exercise.
Time frame: 5 days
Difference of Outcome Measures on Day 1 vs. Remaining Days (Days 2-5) During the Closed-loop Period.
Time frame: 5 Days