NCT02065895

Effect of Gain on Closed-Loop Insulin

• Status: Completed
• Phase: N/A
• Study type: Interventional
• Enrollment: 8 (actual)
• Sponsor: Joslin Diabetes Center · Academic / Other
• Sex: All
• Age: 18 Years – 75 Years
• Healthy volunteers: Not accepted

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

Conditions

• Type 1 Diabetes

Interventions

Type	Name	Description
DEVICE	HIGH error	Overnight and breakfast closed-loop control were performed using a target glucose of 120 mg/dL but with the glucose-value-used-for-control equal to 1.33 times the true glucose value (analogous to higher gain lower target).
DEVICE	NO error	Overnight and breakfast closed-loop control were performed using a target glucose of 120 mg/dL and glucose-value-used-for-control equal to the true glucose value.
DEVICE	LOW error	Overnight and breakfast closed-loop control were performed using a target glucose of 120 mg/dL but with the glucose-value-used-for-control equal to 0.8 times the true glucose value (analogous to lower gain higher target).

Timeline

• Start date: 2013-12-01
• Primary completion: 2015-04-01
• Completion: 2015-04-01
• First posted: 2014-02-19
• Last updated: 2018-05-17
• Results posted: 2018-04-06

Locations

1 site across 1 country: United States