Hybrid closed-loop (HCL) pivotal trial in type 1 diabetes

Richard M. Bergenstal, MD presented results of Hybrid closed-loop (HCL) pivotal trial in type 1 diabetes at EASD meeting (12nd to 16th September 2016) in Munich.

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Richard M. Bergenstal’s interview by MedPage Today

Hybrid closed-loop (HCL) pivotal trial in type 1 diabetes

Background and aims: A hybrid closed-loop (HCL) system was examined in a pivotal trial with the aim to establish the system’s safety for use in adolescents and adults (age 14-75 years) with type 1 diabetes. Materials and methods: The system included the Medtronic MiniMed 670G pump, a fourth-generation glucose sensor, and a proportional-integral-differential control algorithm. Following a 2-week run-in phase to establish baseline parameters, 124 subjects (55 male), with age 37.8±16.5 (range, 14-75) years, diabetes duration 21.7±13.7 years, and HbA1c 7.4±0.9% entered a 3-month study phase. The study phase was followed by an optional continued-access program. Subjects calibrated the sensors periodically and administered mealtime and correction boluses as needed. Sensor glucose (SG) and HbA1c values from baseline and study phases were compared. Glycemic variability was measured by the standard deviation (SD) and coefficient of variation (CV) of SG values. Subjects were categorized according to baseline HbA1c values and within each category, the change in HbA1c was calculated. The change in GV from baseline to the final 2 weeks of the study was also calculated for subjects in each starting HbA1c category.

Results: The HCL auto-mode was used for a median of 87.2% (IQR, 75.0% to 91.7%) of the time after first start. There were higher percentages of SG 71-180 mg/dL, lower percentages of SG ≤70 mg/dL, and lower percentages of SG ≤50 mg/dL during 24 hours and at night (p<0.001 for each) in the study phase compared to baseline (Table). Mean HbA1c decreased from 7.4±0.9% to 6.9±0.6% (overall ΔHbA1c = – 0.5 percentage points) and the proportion of subjects with HbA1c <7% increased from 33.1% to 55.3%. Overall SD decreased from 56.5 mg/dL to 52.5 mg/dL, and CV decreased from 37.6% to 34.7% (p<0.001 for each). For subjects with starting HbA1c <7.0%, ΔHbA1c and ΔSD were -0.1 percentage points and – 4.5 mg/dL. For subjects with starting HbA1c from 7.0% to 7.5%, ΔHbA1c and ΔSD were -0.3 percentage points and -2.1 mg/dL. For subjects with starting HbA1c >7.5%, ΔHbA1c and ΔSD were -1.0 percentage points and -4.7 mg/dL. There was no DKA, severe hypoglycemia, or serious device-related adverse event during 12,389 patient-days of use. At study’s end, 99 patients entered the continued-access program. Conclusion: Subjects with the highest baseline HbA1c values experienced the largest reductions in HbA1c and glycemic variability. The HCL system was safe, acceptable, and associated with improved glucose control during day and nighttime periods during extended at-home use.

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Clinical Trial Registration Number: NCT02463097 Disclosure: R.M. Bergenstal: Grants; Medtronic, Inc.

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