In the Journals

Overnight closed-loop control shows promise in type 1 diabetes

Closed-loop control during the overnight hours significantly improved time in hypoglycemic range compared with a sensor-augmented pump in adults with type 1 diabetes, according to findings published in The Journal of Clinical Endocrinology & Metabolism.

“[Closed-loop control] systems require a patient having trust in an automated system, which may take time to adapt,” the researchers wrote. “Even of those who embrace it, some may find the systems most useful at night rather than during the day. Patients may choose to start using these systems for overnight control only to alleviate the well-documented fear of hypoglycemia while asleep.”

Sue Brown
Sue A. Brown

Sue A. Brown, MD, of the division of endocrinology, Center for Diabetes Technology at the University of Virginia in Charlottesville, and colleagues evaluated 40 adults (mean age, 45.5 years) with type 1 diabetes (mean HbA1c, 7.4%) on insulin pump therapy randomly assigned to sensor-augmented pump therapy at home or 5 nights of closed-loop control in a supervised outpatient setting. Researchers sought to test the safety and efficacy of overnight closed-loop control and determine its effect on glycemic control during a 24-hour period. A subset of 10 participants underwent 5 additional nights of overnight closed-loop control to further assess the system’s durability and its effect on overall control. The main outcome measure was percent time spent in target range (70 mg/dL-180 mg/dL).

The closed-loop control group spent more time in target range (78.3%) compared with the sensor-augmented pump group (71.4%; P = .003) when measured over 24 hours during the study period. The closed-loop control group also had improved time in target during the overnight hours (85.7%) compared with the sensor-augmented pump group (67.6%; P < .001).

Compared with the sensor-augmented pump group, the closed-loop control group had lower mean glucose overnight (137.2 mg/dL vs. 154.9 mg/dL; P < .001), and mean glucose upon awakening was close to the algorithm target of 120 mg/dL and improved (123.7 mg/dL vs. 145.3 mg/dL; P < .001).

During the overall study period and overnight, time in hypoglycemic range (< 70 mg/dL) and time in hyperglycemic range (> 180 mg/dL) were significantly improved in the closed-loop control group compared with the sensor-augmented pump group.

In the subset of participants who used closed-loop control at home, time in hypoglycemic range overall and overnight was lower with closed-loop control (2.2%) compared with sensor-augmented pump (4.9%; P < .05). Hypoglycemia overnight at home was nearly nonexistent in the closed-loop control group (0.6%) compared with the sensor-augmented pump group (3.7%; P = .03). There were no significant differences for time in target range and time above 180 mg/dL between the two groups.

No serious adverse events were reported.

“This study demonstrates the effective use of closed-loop control in improving time in target range over 24 hours and decreasing the chance of hypoglycemia while simultaneously lowering glucose variability even if the closed-loop control system is only used at night,” Brown told Endocrine Today. “This study extends the role of closed-loop systems in improving glycemic control in type 1 diabetes. Hypoglycemia is always a concern in the management of type 1 diabetes, particularly during the nighttime hours. This study highlights the role these closed-loop systems can play in decreasing this risk.” – by Amber Cox

For more information:

Sue A. Brown, MD, can be reached at sab2f@virginia.edu.

Disclosures: Brown reports various financial ties with Animas Corp., Dexcom, Medtronic and Roche Diagnostics. Please see the full study for a list of all other authors’ relevant financial disclosures.

Closed-loop control during the overnight hours significantly improved time in hypoglycemic range compared with a sensor-augmented pump in adults with type 1 diabetes, according to findings published in The Journal of Clinical Endocrinology & Metabolism.

“[Closed-loop control] systems require a patient having trust in an automated system, which may take time to adapt,” the researchers wrote. “Even of those who embrace it, some may find the systems most useful at night rather than during the day. Patients may choose to start using these systems for overnight control only to alleviate the well-documented fear of hypoglycemia while asleep.”

Sue Brown
Sue A. Brown

Sue A. Brown, MD, of the division of endocrinology, Center for Diabetes Technology at the University of Virginia in Charlottesville, and colleagues evaluated 40 adults (mean age, 45.5 years) with type 1 diabetes (mean HbA1c, 7.4%) on insulin pump therapy randomly assigned to sensor-augmented pump therapy at home or 5 nights of closed-loop control in a supervised outpatient setting. Researchers sought to test the safety and efficacy of overnight closed-loop control and determine its effect on glycemic control during a 24-hour period. A subset of 10 participants underwent 5 additional nights of overnight closed-loop control to further assess the system’s durability and its effect on overall control. The main outcome measure was percent time spent in target range (70 mg/dL-180 mg/dL).

The closed-loop control group spent more time in target range (78.3%) compared with the sensor-augmented pump group (71.4%; P = .003) when measured over 24 hours during the study period. The closed-loop control group also had improved time in target during the overnight hours (85.7%) compared with the sensor-augmented pump group (67.6%; P < .001).

Compared with the sensor-augmented pump group, the closed-loop control group had lower mean glucose overnight (137.2 mg/dL vs. 154.9 mg/dL; P < .001), and mean glucose upon awakening was close to the algorithm target of 120 mg/dL and improved (123.7 mg/dL vs. 145.3 mg/dL; P < .001).

During the overall study period and overnight, time in hypoglycemic range (< 70 mg/dL) and time in hyperglycemic range (> 180 mg/dL) were significantly improved in the closed-loop control group compared with the sensor-augmented pump group.

In the subset of participants who used closed-loop control at home, time in hypoglycemic range overall and overnight was lower with closed-loop control (2.2%) compared with sensor-augmented pump (4.9%; P < .05). Hypoglycemia overnight at home was nearly nonexistent in the closed-loop control group (0.6%) compared with the sensor-augmented pump group (3.7%; P = .03). There were no significant differences for time in target range and time above 180 mg/dL between the two groups.

No serious adverse events were reported.

“This study demonstrates the effective use of closed-loop control in improving time in target range over 24 hours and decreasing the chance of hypoglycemia while simultaneously lowering glucose variability even if the closed-loop control system is only used at night,” Brown told Endocrine Today. “This study extends the role of closed-loop systems in improving glycemic control in type 1 diabetes. Hypoglycemia is always a concern in the management of type 1 diabetes, particularly during the nighttime hours. This study highlights the role these closed-loop systems can play in decreasing this risk.” – by Amber Cox

For more information:

Sue A. Brown, MD, can be reached at sab2f@virginia.edu.

Disclosures: Brown reports various financial ties with Animas Corp., Dexcom, Medtronic and Roche Diagnostics. Please see the full study for a list of all other authors’ relevant financial disclosures.