The current study is designed to determine the effect on mean glucose, hypoglycemia, glucagon usage, and insulin usage of adjusting upward the glucose target of the bi-hormonal bionic pancreas, and determine whether there is a target at which adequate glycemic control is achieved by an insulin-only bionic pancreas with minimal hypoglycemia.
We have two specific aims: Aim 1 is to conduct an outpatient study testing multiple configurations of the bionic pancreas in 24 adult subjects with type 1 diabetes in a random cross-over study versus usual care with an insulin pump. These bionic pancreas configurations include the insulin only BP at 145 mg/dl set point, 130 mg/dl set point, 120 mg/dl set point and 110 mg/dl set point and the bihormonal BP at 130 mg/dl set point, 115 mg/dl set point and 110 mg/dl set point. These arms are all compared to usual care. Aim 2 is to evaluate the incremental utility of glucagon in the context of automated insulin delivery by the bionic pancreas in preventing hypoglycemia during exercise in the fasted state. The 130 mg/dl set points and 110 mg/dl set points also participate in this fasted exercise visit. These two set points are double blinded, so neither the subjects nor the study staff are aware which arm is bihormonal and which arm is insulin only.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
24
Participant wears the bionic pancreas, including an insulin and/or glucagon pump depending on which arm they are in. The 100 mg/dl arm for type 1 diabetes patients will deliver insulin and glucagon. The 100 mg/dl arm for type 2 diabetes patients will deliver just insulin. The 115 mg/dl arm will deliver insulin and glucagon. The 120 mg/dl arm will deliver just insulin. The 145 mg/dl arm will deliver just insulin. The 130 mg/dl and 110 mg/dl arms will deliver insulin and placebo, or insulin and glucagon, and will be double blinded.
Participant cares for their diabetes according to their usual practice, with blinded CGM monitoring. No medication will be administered by the study in this intervention.
Masscahusetts General Hospital
Boston, Massachusetts, United States
Mean Continuous Glucose Monitor (CGM) Glucose Values
Glucose values were collected from the Dexcom G4 CGM device every 5 minutes and an average (calculated mean with associated standard deviation) CGM glucose level (mg/dl) was calculated from days 2 and 3 of the study arm.
Time frame: Days 2 and 3
Percentage of Time With CGM < 60 mg/dl
For this calculation we analyzed data from every 5 minutes of CGM data for days 2 and 3 of each study arm. We looked specifically at the percentage time of those roughly 48 hours that had any glucose values less than 60 mg/dl. The final value presented is the percent of time per 2 days of the study arm spent in a specific hypoglycemia range of less than 60 mg/dl with an associated standard deviation.
Time frame: Days 2 and 3
Number of Subjects Discordant for Reaching a BG < 60 mg/dl for > 2 Consecutive Plasma Glucose Measurements During Inpatient Exercise Visit
During both 110 mg/dl and 130 mg/dl arms, subjects will report for a fasted in-clinic exercise visit, with plasma blood glucose measurements obtained at least every 10 minutes
Time frame: Day 4 in-clinic Exercise Visit (110 and 130 mg/dl arms only)
Mean CGM Glucose
Average glucose according to continuous glucose monitor readings including the 1 day washout
Time frame: Days 1 through 3
Nausea Severity
The average severity of nausea, as recorded on a 10 centimeter visual analog scale by the daily e-mail survey they receive. Scores were determined by how many centimeters the subject marked as a surrogate for their nausea level on a daily basis. Any value more than 0 cm indicates some degree of nausea with a score of 10 cm being the worst nausea imaginable. A score less than 3 cm indicates a mild level of nausea.
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Time frame: Days 1-3
Percentage of Time Spent in: < 50 mg/dl, < 70 mg/dl, 70-120 mg/dl, 70-180 mg/dl, > 180 mg/dl, >250 mg/dl
The fraction of time spent in each of these ranges according to continuous glucose monitor readings
Time frame: Days 2-3
Percentage of Subjects With Mean CGM < 154 mg/dl
The percentage of subjects who's mean CGM glucose level is \< 154 mg/dl, which is an estimated hemoglobin a1c \< 7%, which is the ADA goal for therapy
Time frame: Days 2-3
Area Between the Glucose Curve and 60 mg/dl Calculated From BG Measurements
Plasma glucose values to create this curve included time points from time 0 to a maximum of 360 minutes, with a sampling frequency of at least every 10 minutes throughout.
Time frame: Day 4 in-clinic Exercise Visit (110 and 130 mg/dl arms only)
Area Between the Glucose Curve and 60 mg/dl Calculated From CGM Measurements
CGM glucose values to create this curve included time points from time 0 to a maximum of 360 minutes, with a sampling frequency of every 5 minutes
Time frame: Day 4 in-clinic Exercise Visit (type 1 diabetes only, 110 and 130 mg/dl arms only)
Time From Start of Exercise to First BG Measurement < 60 mg/dl
During both 110 mg/dl and 130 mg/dl arms, subjects will report for a fasted in-clinic exercise visit, with plasma blood glucose measurements obtained at least every 10 minutes
Time frame: Day 4 in-clinic Exercise Visit (type 1 diabetes only, 110 and 130 mg/dl arms only)
Time From Start of Exercise to First CGM Measurement < 60 mg/dl
During both 110 mg/dl and 130 mg/dl arms, subjects will report for a fasted in-clinic exercise visit, with plasma blood glucose measurements obtained at least every 10 minutes
Time frame: Day 4 in-clinic Exercise Visit (110 and 130 mg/dl arms only)
Grams of Carbohydrates Given to the Subject to Treat Hypoglycemia
During both 110 mg/dl and 130 mg/dl arms, subjects will report for a fasted in-clinic exercise visit, with plasma blood glucose measurements obtained at least every 10 minutes
Time frame: Day 4 in-clinic Exercise Visit (110 and 130 mg/dl arms only)
Total Glucagon Dosing by the Bihormonal Bionic Pancreas From the Start of Exercise Until the End of the Visit
During both 110 mg/dl and 130 mg/dl arms, subjects will report for a fasted in-clinic exercise visit, with plasma blood glucose measurements obtained at least every 10 minutes
Time frame: Day 4 in-clinic Exercise Visit (110 and 130 mg/dl arms only)