Effect of Gain on Closed-Loop Insulin

Not Applicable

Completed

Conditions: Type 1 Diabetes

Interventions: Device: HIGH error
Device: NO error
Device: LOW error

Registration Number: NCT02065895

Lead Sponsor: Joslin Diabetes Center

Brief Summary: The purpose of this study is to test the ability of an advanced external Physiologic Insulin Delivery (ePID) algorithm (a step by step process used to develop a solution to a problem) to get acceptable meal responses over a range of gain. Gain is defined as how much insulin is given in response to a change in a patient's glucose level.

This study also examines the effectiveness of the external Physiologic Insulin Delivery (ePID) closed-loop insulin delivery computer software. The investigators would like to assess whether fasting target levels can be achieved as the closed-loop gain increases or decreases, and to evaluate the system's ability to produce an acceptable breakfast meal response.

Detailed Description: There have been significant advances in diabetes management technology, including more sophisticated insulin pumps and more accurate real-time continuous glucose monitors. The next technological development is widely thought to be the introduction of an algorithm linking the pump and sensor to form a closed-loop insulin delivery system. The algorithm used for this purpose needs to be robust to changes in an individual's insulin sensitivity, and the sensor's sensitivity to glucose. Insulin sensitivity (how much the patient's glucose level changes in response to a change in insulin delivery) and algorithm gain (how much insulin is delivered in response to a change in glucose) determine the systems overall closed-loop gain. Ideally, the overall gain can be set to achieve the lowest possible peak postprandial glucose response without postprandial hypoglycemia. However, if the algorithm's gain is set to a fixed value and the subject's insulin sensitivity changes, the overall-gain will change. Some degradation in closed-loop performance might be acceptable during periods whenever the subject's insulin sensitivity is low (i.e., the subject is insulin resistant) and the risk of hypoglycemia may actually be reduced. However, if the subject becomes more sensitive the system may become less stable and the risk of postprandial hypoglycemia may increase. In addition to changes in insulin sensitivity, glucose sensors will sometimes over- or under-read blood glucose as sensor sensitivity increases or decreases. This will result in a change in the closed-loop algorithm's effective target. The purpose of this study is to evaluate the ability of an advanced Physiologic Insulin Delivery algorithm to achieve an acceptable breakfast response as the gain and effective target glucose level changes. Specifically:

1. to assess the fasting glucose levels achieved as the overall closed-loop gain and effective target is increased or decreased, and

2. determine the system's ability to produce an acceptable breakfast meal response under these conditions

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 8

Inclusion Criteria

Type 1 diabetes for > 3 years
Manage diabetes using a continuous glucose monitor and continuous subcutaneous insulin infusion pump
Non obese (BMI < 30)
Aged 18 - 75 years old
HbA1c < 8 %

Exclusion Criteria

renal or hepatic failure
cancer or lymphoma
Malabsorption or malnourishment
Hypercortisolism
Alcoholism or drug abuse
Anemia (hematocrit < 36 in females and <40 in males)
Eating disorder
Dietary restrictions
Acetaminophen allergy
Chronic acetaminophen use
Glucocorticoid therapy
History of gastroparesis
Use of Beta blockers

Study & Design

Study Type: INTERVENTIONAL

Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
HIGH error, LOW error, NO error	LOW error	Subjects were randomized to receive overnight and breakfast closed-loop glucose control glucose on three occasions: first with glucose-value-used-for-control higher than blood glucose (HIGH error), then second with glucose-value-used-for-control lower than blood glucose (LOW error), then third with glucose-value-used-for-control equal blood glucose (NO error).
HIGH error, NO error, LOW error	LOW error	Subjects were randomized to receive overnight and breakfast closed-loop glucose control glucose on three occasions: first with glucose-value-used-for-control higher than blood glucose (HIGH error), then second with glucose-value-used-for-control equal blood glucose (NO error), then third with glucose-value-used-for-control lower than blood glucose (LOW error).
NO error, HIGH error, LOW error	NO error	Subjects were randomized to receive overnight and breakfast closed-loop glucose control glucose on three occasions: first with glucose-value-used-for-control equal blood glucose (NO error), then second with glucose-values-used-for-control higher than blood glucose (HIGH error), then third with glucose-value-used-for-control lower than blood glucose (LOW error).
NO error, LOW error, HIGH error	NO error	Subjects were randomized to receive overnight and breakfast closed-loop glucose control glucose on three occasions: first with glucose-value-used-for-control equal blood glucose (NO error), then second with glucose-value-used-for-control lower than blood glucose (LOW error), then third with glucose-value-used-for-control higher than blood glucose (HIGH error).
LOW error, HIGH error, NO error	HIGH error	Subjects were randomized to receive overnight and breakfast closed-loop glucose control glucose on three occasions: first with glucose-value-used-for-control lower than blood glucose (LOW error), then second with glucose-value-used-for-control equal blood glucose (NO error), then third glucose-value-used-for-control higher than blood glucose (HIGH error),
LOW error, HIGH error, NO error	NO error	Subjects were randomized to receive overnight and breakfast closed-loop glucose control glucose on three occasions: first with glucose-value-used-for-control lower than blood glucose (LOW error), then second with glucose-value-used-for-control equal blood glucose (NO error), then third glucose-value-used-for-control higher than blood glucose (HIGH error),
HIGH error, LOW error, NO error	HIGH error	Subjects were randomized to receive overnight and breakfast closed-loop glucose control glucose on three occasions: first with glucose-value-used-for-control higher than blood glucose (HIGH error), then second with glucose-value-used-for-control lower than blood glucose (LOW error), then third with glucose-value-used-for-control equal blood glucose (NO error).
HIGH error, NO error, LOW error	NO error	Subjects were randomized to receive overnight and breakfast closed-loop glucose control glucose on three occasions: first with glucose-value-used-for-control higher than blood glucose (HIGH error), then second with glucose-value-used-for-control equal blood glucose (NO error), then third with glucose-value-used-for-control lower than blood glucose (LOW error).
NO error, LOW error, HIGH error	LOW error	Subjects were randomized to receive overnight and breakfast closed-loop glucose control glucose on three occasions: first with glucose-value-used-for-control equal blood glucose (NO error), then second with glucose-value-used-for-control lower than blood glucose (LOW error), then third with glucose-value-used-for-control higher than blood glucose (HIGH error).
HIGH error, LOW error, NO error	NO error	Subjects were randomized to receive overnight and breakfast closed-loop glucose control glucose on three occasions: first with glucose-value-used-for-control higher than blood glucose (HIGH error), then second with glucose-value-used-for-control lower than blood glucose (LOW error), then third with glucose-value-used-for-control equal blood glucose (NO error).
HIGH error, NO error, LOW error	HIGH error	Subjects were randomized to receive overnight and breakfast closed-loop glucose control glucose on three occasions: first with glucose-value-used-for-control higher than blood glucose (HIGH error), then second with glucose-value-used-for-control equal blood glucose (NO error), then third with glucose-value-used-for-control lower than blood glucose (LOW error).
NO error, HIGH error, LOW error	HIGH error	Subjects were randomized to receive overnight and breakfast closed-loop glucose control glucose on three occasions: first with glucose-value-used-for-control equal blood glucose (NO error), then second with glucose-values-used-for-control higher than blood glucose (HIGH error), then third with glucose-value-used-for-control lower than blood glucose (LOW error).
NO error, HIGH error, LOW error	LOW error	Subjects were randomized to receive overnight and breakfast closed-loop glucose control glucose on three occasions: first with glucose-value-used-for-control equal blood glucose (NO error), then second with glucose-values-used-for-control higher than blood glucose (HIGH error), then third with glucose-value-used-for-control lower than blood glucose (LOW error).
LOW error, NO error, HIGH error	LOW error	Subjects were randomized to receive overnight and breakfast closed-loop glucose control glucose on three occasions: first with with glucose-value-used-for-control lower than blood glucose (LOW error), then second with glucose-value-used-for-control equal blood glucose (NO error), then third with glucose-value-used-for-control higher than blood glucose (HIGH error).
NO error, LOW error, HIGH error	HIGH error	Subjects were randomized to receive overnight and breakfast closed-loop glucose control glucose on three occasions: first with glucose-value-used-for-control equal blood glucose (NO error), then second with glucose-value-used-for-control lower than blood glucose (LOW error), then third with glucose-value-used-for-control higher than blood glucose (HIGH error).
LOW error, NO error, HIGH error	HIGH error	Subjects were randomized to receive overnight and breakfast closed-loop glucose control glucose on three occasions: first with with glucose-value-used-for-control lower than blood glucose (LOW error), then second with glucose-value-used-for-control equal blood glucose (NO error), then third with glucose-value-used-for-control higher than blood glucose (HIGH error).
LOW error, NO error, HIGH error	NO error	Subjects were randomized to receive overnight and breakfast closed-loop glucose control glucose on three occasions: first with with glucose-value-used-for-control lower than blood glucose (LOW error), then second with glucose-value-used-for-control equal blood glucose (NO error), then third with glucose-value-used-for-control higher than blood glucose (HIGH error).
LOW error, HIGH error, NO error	LOW error	Subjects were randomized to receive overnight and breakfast closed-loop glucose control glucose on three occasions: first with glucose-value-used-for-control lower than blood glucose (LOW error), then second with glucose-value-used-for-control equal blood glucose (NO error), then third glucose-value-used-for-control higher than blood glucose (HIGH error),

Primary Outcome Measures

Name	Time	Method
Glucose Area Under the Curve (AUC) Breakfast	On day #1, day #2 and day #3 (each day could be 24 hours to 7 days apart from prior one, and completed within 6 week period) 8:00 AM to 2:00 PM on day following admission, with samples obtained every 10-15 minutes, for each sequence of calibration errors	Glucose Area Under the Curve (AUC) Breakfast defines the total exposure to glucose during breakfast. Breakfast is typically considered the most difficult meal to control; low AUC is desirable.This outcome measure was analyzed for each of the three calibration error values (high error, no error and low error).

Secondary Outcome Measures

Name	Time	Method
Peak and Nadir Postprandial Glucose Concentration	On day #1, day #2 and day #3 (each day could be 24 hours to 7 days apart from prior one, and completed within 6 week period) 8:00 AM to 12:00 PM on day following admission, with samples obtained every 10-15 minutes, for each sequence of calibration errors	Highest and lowest glucose concentrations obtained during breakfast meal.