Comparison of Day and Night Closed-loop With Faster-acting Insulin Aspart With Insulin Aspart

This is an open-label, single-centre, two-period, randomised, cross over study. The study involves a screening visit to assess participant eligibility and two 24 hour in-patient stays at the clinical research facility during which day and night glucose levels will be controlled by the closed-loop system with either faster-acting insulin aspart or insulin aspart.

Up to 22 adults with type 1 diabetes and treated with continuous subcutaneous insulin infusion will be recruited, aiming for 16 completed participants. Recruitment will take place at Manchester Diabetes Centre, Manchester Royal Infirmary, Manchester, UK. Participants will attend the Manchester Clinical Research Facility (MCRF), Manchester, on two occasions. In random order, they will undergo two closed-loop study days using either faster-acting insulin aspart or insulin aspart. During the study days, the closed-loop control algorithm will automatically modulate d insulin infusion rate based on real-time subcutaneous glucose sensor measurements. Participants will receive standardised meals with half usual meal bolus for the evening meal and no meal bolus for lunch time meal during each study day.

Inclusion criteria

• The subject is 18 years and older
• The subject has type 1 diabetes, as defined by WHO for at least 1 year or is confirmed C-peptide negative
• The subject will have been an insulin pump user for at least 3 months
• The subject is treated with any of the rapid acting insulin analogues
• The subject is willing to adhere to study procedures
• HbA1c ≥ 7.0% (53 mmol/mol) and ≤ 10 % (86mmol/mol) based on analysis from local laboratory or equivalent within 3 months prior to enrolment
• The subject is literate in English

Exclusion criteria

• 1. Non-type 1 diabetes mellitus including those secondary to chronic disease 2. Any other physical or psychological disease likely to interfere with the normal conduct of the study 3. Untreated celiac disease or hypothyroidism 4. Current treatment with drugs known to interfere with glucose metabolism, e.g. systemic corticosteroids, Metformin, SGLT2 inhibitors, non-selective beta-blockers and MAO inhibitors etc.

• Known or suspected allergy against insulin 6. Subjects with clinical significant nephropathy, neuropathy or proliferative retinopathy as judged by the investigator 7. Total daily insulin dose > 2 U/kg/day 8. Total daily insulin dose < 10 U/day 9. Pregnancy, planned pregnancy, or breast feeding