Background: We assessed whether improved glucose control with hybrid closed loop can preserve C-peptide secretion compared to standard insulin therapy in youth with T1D.

Methods: In a multicentre, randomised, parallel trial, youth aged to <17 yrs were randomised within 21 days of T1D diagnosis to hybrid closed loop using Cambridge algorithm (CL) or standard insulin therapy (control) for 24 months. Analysis was by intention to treat.

Results: We randomised 97 participants (mean±SD age 12±2 yrs) , 51 to CL and 46 to control. There was no difference in C-peptide AUC at 12 months (primary endpoint) or 24 months between groups (geometric mean [95% CI] 12 months CL: 0.35 pmol/mL [0.27, 0.43] vs. control: 0.46 pmol/mL [0.33, 0.61]; mean adjusted difference -0.[-0.14 to 0.03]; p=0. and 24 months CL: 0.17 pmol/mL [0.12, 0.23] vs. control: 0.25 pmol/mL [0.12, 0.39]; mean adjusted difference -0.[-0.14 to 0.05]; p=0.25) . Glycated haemoglobin was lower in the CL group by 4 mmol/mol [0.4%] (95% CI 0 to 8 mmol/mol [0.0 to 0.7%]) at 12 months, and mmol/mol [0.9%], (95% CI 7 to 15 mmol/mol [0.4 to 1.5%]; p<0.001) at 24 months. Five severe hypoglycaemic events occurred in CL group (3 participants) , and two in control group (2 participants) ; one DKA occurred in the CL group.

Conclusions: In new onset T1D, optimising glucose control for 24 months does not appear to prevent the decline in residual C-peptide secretion.


C.K. Boughton: Consultant; CamDiab Ltd. J. Ware: None. J.M. Allen: None. M.E. Wilinska: Consultant; CamDiab Ltd. S. Hartnell: Advisory Panel; Medtronic. Speaker's Bureau; Dexcom, Inc., Sanofi. Other Relationship; Ask Diabetes Ltd. A. Thankamony: None. T. Randell: Consultant; Abbott Diabetes. Speaker's Bureau; Novo Nordisk. A. Ghatak: None. D. Elleri: None. R. Bailey: None. G.J. Dunseath: None. R. Hovorka: Advisory Panel; Eli Lilly and Company. Research Support; Abbott Diabetes, Dexcom, Inc., Medtronic. Speaker's Bureau; Dexcom, Inc., Eli Lilly and Company, Novo Nordisk. Other Relationship; CamDiab Ltd.


National Institute for Health Research EME Grant (14/23/09) Leona M & Harry B Helmsley Charitable Trust Grant (#2016PG-T1D046) Additional support for the artificial pancreas work is from National Institute for Health Research Cambridge Biomedical Research Centre, and Wellcome Strategic Award (100574/Z/12/Z) . Medtronic and Dexcom supplied discounted CGM devices, sensors and details of communication protocol to facilitate real-time connectivity. Abbott Diabetes Care provided Libre Pro sensors.

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