Bolusing frequency and amount impacts glucose control during hybrid closed-loop.

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Bally, L 
Ruan, Y 
Mader, JK 
Kojzar, H 

AIM: To compare bolus insulin delivery patterns during closed-loop home studies in adults with suboptimally [HbA1c 58-86 mmol/mol (7.5%-10%)] and well-controlled [58 mmol/mol (< 7.5%)] Type 1 diabetes. METHODS: Retrospective analysis of daytime and night-time insulin delivery during home use of closed-loop over 4 weeks. Daytime and night-time controller effort, defined as amount of insulin delivered by closed-loop relative to usual basal insulin delivery, and daytime bolus effort, defined as total bolus insulin delivery relative to total daytime insulin delivery were compared between both cohorts. Correlation analysis was performed between individual bolus behaviour (bolus effort and frequency) and daytime controller efforts, and proportion of time spent within and below sensor glucose target range. RESULTS: Individuals with suboptimally controlled Type 1 diabetes had significantly lower bolus effort (P = 0.038) and daily bolus frequency (P < 0.001) compared with those with well-controlled diabetes. Controller effort during both daytime (P = 0.007) and night-time (P = 0.005) were significantly higher for those with suboptimally controlled Type 1 diabetes. Time when glucose was within the target range (3.9-10.0 mmol/L) during daytime correlated positively with bolus effort (r = 0.37, P = 0.016) and bolus frequency (r = 0.33, P = 0.037). Time when glucose was below the target range during daytime was comparable in both groups (P = 0.36), and did not correlate significantly with bolus effort (r = 0.28, P = 0.066) or bolus frequency (r = -0.21, P = 0.19). CONCLUSION: More frequent bolusing and higher proportion of insulin delivered as bolus during hybrid closed-loop use correlated positively with time glucose was in target range. This emphasises the need for user input and educational support to benefit from this novel therapeutic modality.

Adult, Blood Glucose, Diabetes Mellitus, Type 1, Female, Glycated Hemoglobin, Home Care Services, Humans, Hypoglycemic Agents, Insulin, Insulin Infusion Systems, Male, Retrospective Studies
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Diabet Med
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Wellcome Trust (100574/Z/12/Z)
National Institute of Diabetes and Digestive and Kidney Diseases (R01DK085621)
European Commission (247138)
Department of Health (via National Institute for Health Research (NIHR)) (EME 14/23/09)
National Institute of Diabetes and Digestive and Kidney Diseases (DP3DK112176)
Juvenile Diabetes Research Foundation Ltd (JDRF) (2-SRA-2014-256-M-R)
National Institute of Diabetes and Digestive and Kidney Diseases (UC4DK108520)
Helmsley Charitable Trust (#2016PG-T1D045)
Helmsley Charitable Trust (#2016PG-T1D046)
European Commission Horizon 2020 (H2020) Societal Challenges (731560)
NIHR Evaluation Trials and Studies Coordinating Centre (14/23/09)
Seventh Framework Programme of the European Union (ICT FP7- 247138). Additional support for the Artificial Pancreas work by JDRF, National Institute for Health Research Cambridge Biomedical Research Centre, Wellcome Strategic Award (100574/Z/12/Z), EC Horizon 2020 (H2020-SC1-731560), NIDDK (DP3DK112176 and 1UC4DK108520-01), Efficacy and Mechanism Evaluation Programme of National Institute for Health Research (14/23/09) and Helmsley Trust (2016PG-T1D045 and #2016PG-T1D046).