• Diabetes Mellitus
• Hyperglycemia/Hypoglycemia
• Diabetes & Endocrinology Clinical Trials

• Diabetes Mellitus
• Hyperglycemia/Hypoglycemia
• Diabetes & Endocrinology Clinical Trials
• Endocrinology
• Diabetes & Metabolic Syndrome

Twenty-four-hour glucose control using a closed-loop system was feasible and resulted in improved glucose control without increasing hypoglycemic events, according to data presented by Lalantha Leelarathna, PhD, University of Cambridge, Cambridge, United Kingdom, from the Closing the Loop in Adults With Sub-optimally Controlled Type 1 Diabetes Under Free Living Conditions study [AP@home02; NCT01666028]. The purpose of the AP@home02 study was to determine the feasibility of using a closed-loop insulin delivery system, combining an insulin pump and continuous glucose monitoring (CGM), for glucose control for 7 days in patients with type 1 diabetes mellitus (T1DM).

In this multinational (3 centers) crossover study, 17 (7 women) adult patients with T1DM were randomly assigned to open-loop or closed-loop glucose control for 7 days and then crossed over to the other modality for another 7 days. Prior to each at-home monitoring period, patients were monitored at the Clinical Research Center (CRC) for 23 hours. All patients received training on CGM and the closed-loop system during the run-in period.

The mean age of the study patients was 34 years, body mass index was 26.2 kg/m², and HbA1C was 7.6%. The mean duration of diabetes was 19 years, mean total daily insulin was 40.1 U, and total daily insulin per kilogram per day was 0.53 U.

In the CRC, patients had regular venous sampling, and insulin was given as a bolus 15 minutes before meals using a pump bolus calculator. No bolus was given for snacks during visits for the closed-loop system. At home and work, patients used the closed-loop system without supervision, but 24-hour telephone support was available.

The primary endpoint of glucose within the target range of 3.9 and 10.0 mmol/L during home use was achieved by 75% of patients during the closed-loop phase (95% CI, 62 to 82) compared with 63% during the open-loop phase (95% CI, 55 to 72; p = .006). Mean glucose levels were 8.1 mmol/L in the closed-loop arm compared with 8.8 mmol/L in the open-loop arm (p = .027). When stratified by time of day, the closed-loop system resulted in a greater amount of time in target glucose for both daytime (73%; 95% CI, 63 to 79) and nighttime (48%; 95% CI, 33 to 65) compared with the open-loop system (daytime, 65%; 95% CI, 55 to 71; p = .017; and nighttime, 35%; 95% CI, 28 to 48; p = .013). Insulin infusion with both systems during the home phase is detailed in Table 1.

In the utility analysis, the closed-loop system was operational 83% of the time during the home phase and 98% during the inpatient stay. Undesirable stopping of the closed-loop system occurred due to lack of pump connectivity or CGM availability, the user changing the pump settings, or other unknown reasons.

Adverse events included two severe hypoglycemic episodes; neither was during closed-loop operation, and both patients fully recovered. In one case, the sensor was not working. Four episodes of high glucose occurred because of failure of the insulin infusion system, but there was no ketosis or hospital admission.

In conclusion, Dr. Leelarathna stated these data suggest that day and night closed-loop glucose control is feasible to perform at home and may result in improved glucose control. Next, they will compare a closed-loop system and optimized sensor-augmented pump therapy in 30 patients at home for day and night control.

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