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; Draxlbauer, Katharine; Elleri, Daniela; Evans, Mark L; Fröhlich-Reiterer, Elke; Ghatak, Atrayee; Hofer, Sabine E; Kapellen, Thomas M; Leelarathna, Lalantha; Mader, Julia K; Mubita, Womba M; ... (2024). Safety of User-Initiated Intensification of Insulin Delivery Using Cambridge Hybrid Closed-Loop Algorithm. Journal of diabetes science and technology, 18(4), pp. 882-888. Diabetes Technology Society 10.1177/19322968221141924

19322968221141924.pdf - Published Version
Available under License Creative Commons: Attribution (CC-BY).

Download (532kB) | Preview


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.


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.


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).


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.

Item Type:

Journal Article (Original Article)


04 Faculty of Medicine > Department of Gynaecology, Paediatrics and Endocrinology (DFKE) > Clinic of Endocrinology, Diabetology and Clinical Nutrition

UniBE Contributor:

Bally, Lia Claudia


600 Technology > 610 Medicine & health




Diabetes Technology Society




Pubmed Import

Date Deposited:

13 Dec 2022 15:08

Last Modified:

02 Jul 2024 00:11

Publisher DOI:


PubMed ID:


Uncontrolled Keywords:

artificial pancreas automated insulin delivery closed-loop hypoglycemia personalized medicine type 1 diabetes




Actions (login required)

Edit item Edit item
Provide Feedback