Impact of Hybrid Closed Loop Therapy on Hypoglycemia Awareness in Individuals with Type 1 Diabetes and Impaired Hypoglycemia Awareness

Marie-Anne Burckhardt, Mary B Abraham, Julie Dart, Grant Smith, Niru Paramalingam, Joanne O'Dea, Martin de Bock, Elizabeth Davis, Timothy Jones

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)
229 Downloads (Pure)


Abstract Objective: This study evaluated the efficacy of using a hybrid closed loop (HCL) system in restoring hypoglycemia awareness in individuals with impaired awareness of hypoglycemia (IAH). Research design and methods: Participants with IAH (Gold Score ≥4) were recruited into a randomized crossover pilot study. They participated in two 8-week periods using a HCL system (Medtronic 670GTM) (intervention) and standard insulin pump therapy (control). Hyperinsulinemic hypoglycemic clamp studies were undertaken at baseline and at the end of each study period for the evaluation of the counter-regulatory hormonal and symptomatic responses to hypoglycemia. Results: Seventeen participants (mean age (SD) 35.8y (11.2y)) were included in the study. Peak epinephrine levels (median, IQR) in response to hypoglycemia were similar post intervention and control periods; 234.7 pmol/L (109.2; 938.9) vs 188.3 pmol/L (133.7; 402.9), p=0.233. However, both peak adrenergic and neuroglycopenic symptom scores were higher after intervention; 5.0 (4.5; 9.0) vs 4.0 (4.0; 5.5), p=0.009, and 8.5 (6.0; 15.0) vs 6.5 (6.0; 7.0) p=0.014, respectively. Self-reported hypoglycemia awareness improved: median (IQR) Gold score was 4.0 (3.0; 5.5) vs 5.5 (4.5; 6.0); intervention vs control, p=0.033. Time spent <3.9mmol/L and <3.0mmol/L was lower in the intervention group compared to control, p=0.002. Other patient reported outcomes (hypoglycemia fear and diabetes treatment satisfaction) did not change. Conclusions: A short-term use of a HCL system failed to demonstrate an improvement in counter-regulatory hormonal responses. However, higher hypoglycemia symptom scores during controlled hypoglycemia, better self-reported hypoglycemia awareness and less time spent in hypoglycemia suggest the potential benefits of a HCL system in people with IAH. Key words: Type 1 diabetes, hypoglycemia, hypoglycemia awareness, hybrid-closed loop system.
Original languageEnglish
Pages (from-to)482-490
Number of pages9
JournalDiabetes Technology & Therapeutics
Issue number7
Publication statusPublished - 1 Jul 2021


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