Safety of user-initiated intensification of insulin delivery using Cambridge hybrid closed-loop algorithm.
Ware, Julia Wilinska, Malgorzata E Ruan, Yue Allen, Janet M Boughton, Charlotte K Hartnell, Sara Bally, Lia de Beaufort, Carine Besser, Rachel E J Campbell, Fiona M
Ware, Julia
Wilinska, Malgorzata E
Ruan, Yue
Allen, Janet M
Boughton, Charlotte K
Hartnell, Sara
Bally, Lia
de Beaufort, Carine
Besser, Rachel E J
Campbell, Fiona M
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2022-12-08
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Abstract
Objective: Many hybrid closed-loop (HCL) systems struggle to manage unusually high glucose levels as experienced with intercurrent illness or pre-menstrually. Manual correction boluses may be needed, increasing hypoglycemia risk with overcorrection. The Cambridge HCL system includes a user-initiated algorithm intensification mode ("Boost"), activation of which increases automated insulin delivery by approximately 35%, while remaining glucose-responsive. In this analysis, we assessed the safety of "Boost" mode.
Methods: We retrospectively analyzed data from closed-loop studies involving young children (1-7 years, n = 24), children and adolescents (10-17 years, n = 19), adults (≥24 years, n = 13), and older adults (≥60 years, n = 20) with type 1 diabetes. Outcomes were calculated per participant for days with ≥30 minutes of "Boost" use versus days with no "Boost" use. Participants with <10 "Boost" days were excluded. The main outcome was time spent in hypoglycemia <70 and <54 mg/dL.
Results: Eight weeks of data for 76 participants were analyzed. There was no difference in time spent <70 and <54 mg/dL between "Boost" days and "non-Boost" days; mean difference: -0.10% (95% confidence interval [CI] -0.28 to 0.07; P = .249) time <70 mg/dL, and 0.03 (-0.04 to 0.09; P = .416) time < 54 mg/dL. Time in significant hyperglycemia >300 mg/dL was 1.39 percentage points (1.01 to 1.77; P < .001) higher on "Boost" days, with higher mean glucose and lower time in target range (P < .001).
Conclusions: Use of an algorithm intensification mode in HCL therapy is safe across all age groups with type 1 diabetes. The higher time in hyperglycemia observed on "Boost" days suggests that users are more likely to use algorithm intensification on days with extreme hyperglycemic excursions.
Citation
Ware J, Wilinska ME, Ruan Y, Allen JM, Boughton CK, Hartnell S, Bally L, de Beaufort C, Besser REJ, Campbell FM, Draxlbauer K, Elleri D, Evans ML, Fröhlich-Reiterer E, Ghatak A, Hofer SE, Kapellen TM, Leelarathna L, Mader JK, Mubita WM, Narendran P, Poettler T, Rami-Merhar B, Tauschmann M, Randell T, Thabit H, Thankamony A, Trevelyan N, Hovorka R. Safety of User-Initiated Intensification of Insulin Delivery Using Cambridge Hybrid Closed-Loop Algorithm. J Diabetes Sci Technol. 2024 Jul;18(4):882-888. doi: 10.1177/19322968221141924. Epub 2022 Dec 8.
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Article