We evaluated the impact of baseline A1c on the performance of day-and-night hybrid closed-loop (CL) applying Cambridge control algorithm over 4 weeks in adults with type 1 diabetes. We combined data from 3 multi-national randomized studies [N=85; three groups defined: A1c <7.5% (N=28, 6.8±0.4%; mean±SD), 7.5 to 8.49% (N=32, 7.9±0.3%) and ≥8.5% (N=25, 9.0±0.4%)]. No differences were observed in the duration of diabetes (p=0.79), age (p=0.85) or BMI (p=0.27) between groups, but the mean pre-study total daily insulin dose was higher in those with higher A1c (0.53 vs. 0.59 vs. 0.64 U/kg/day, respectively, p=0.017). Individuals with lower baseline A1c achieved a higher time in range (70-180 mg/dl) and lower mean glucose by reducing time spent >180 mg/dl without an increase in the time <70 mg/dl (Table). Median time <54 mg/dl was low in all groups (0.5%, 0.4% and 0.2%, p=0.37). Total daily insulin dose, % of bolus insulin and the controller effort, defined as the amount of insulin delivered by closed-loop relative to usual basal, were significantly different between groups (p=0.001). Despite significantly higher controller effort, those with higher baseline A1c achieved a lower time in target range than those with lower A1c, who administer a higher percentage of insulin as bolus insulin, which is outside the control of hybrid CL. Education about optimal bolus use may achieve better outcomes with hybrid CL.

L. Leelarathna: Advisory Panel; Self; Abbott, Dexcom, Inc., Medtronic, Novo Nordisk A/S, Roche Diabetes Care, Sanofi-Aventis. Research Support; Self; Dexcom, Inc., Novo Nordisk Inc. Speaker's Bureau; Self; Insulet Corporation, Medtronic, Novo Nordisk A/S, Roche Diabetes Care, Sanofi. H. Thabit: Research Support; Self; Dexcom, Inc. M.E. Wilinska: None. L. Bally: None. J.K. Mader: Advisory Panel; Self; Boehringer Ingelheim International GmbH, Eli Lilly and Company, Prediktor Medical, Roche Diabetes Care, Sanofi. Speaker's Bureau; Self; Abbott, AstraZeneca, Dexcom, Inc., Novo Nordisk Inc. Stock/Shareholder; Self; decide Clinical Software GmbH. S. Arnolds: None. T.R. Pieber: Advisory Panel; Self; ADOCIA, Arecor Limited, AstraZeneca, Novo Nordisk A/S, Sanofi. Speaker's Bureau; Self; Novo Nordisk A/S. V.N. Shah: Advisory Panel; Self; Sanofi US. Consultant; Self; Dexcom, Inc. A. Carlson: Consultant; Self; Sanofi US. Research Support; Self; Abbott, Dexcom, Inc., JDRF, Medtronic, National Institutes of Health, Novo Nordisk A/S. R.M. Bergenstal: Research Support; Self; Abbott, Boehringer Ingelheim Pharmaceuticals, Inc., Dexcom, Inc., Glooko, Inc., Hygieia, JDRF, Johnson & Johnson Medical Devices Companies, Lilly Diabetes, Medtronic MiniMed, Inc., Merck & Co., Inc., National Institute of Diabetes and Digestive and Kidney Diseases, Novo Nordisk Inc., Roche Diabetes Care, Sanofi. Other Relationship; Self; Abbott, Helmsley Charitable Trust, Hygieia, Lilly Diabetes, Novo Nordisk Inc., Onduo LLC, Sanofi, UnitedHealth Group Inc. M. Evans: Advisory Panel; Self; Dexcom, Inc., Medtronic, Roche Diabetes Care, Zucara Therapeutics Inc. Research Support; Self; MedImmune, Sanofi. Speaker's Bureau; Self; AstraZeneca. Other Relationship; Self; Abbott, Eli Lilly and Company, Novo Nordisk Inc. R. Hovorka: Advisory Panel; Self; Novo Nordisk A/S. Research Support; Self; Abbott, Dexcom, Inc., Medtronic. Speaker's Bureau; Self; Eli Lilly and Company, Novo Nordisk A/S. Other Relationship; Self; B. Braun Medical Inc., Medtronic.


JDRF; European Union; National Institute for Health Research Cambridge Biomedical Research Centre; Medtronic; Abbott Diabetes care

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