| Outcome Measures: |
Primary: Percentage of time of plasma glucose levels spent in target range (semaglutide vs placebo), Target range is defined to be between 3.9 and 10.0 mmol/L of placebo on closed-loop system vs semaglutide (at maximal tolerated dose) on closed-loop insulin system., 4 weeks | Secondary: Percentage of time spent in the following ranges of glucose levels between 3.9 and 7.8 mmol/L, % as per CGM data, 4 weeks|Percentage of time spent in the following ranges of glucose levels: below 3.9 and 3.0 mmol/L, % as per CGM data, 4 weeks|Percentage of time spent in the following ranges of glucose levels: above 7.8, 10, and 13.9 mmol/L, % as per CGM data, 4 weeks|Mean glucose level, Defined as per CGM data, in mmol/L, 4 weeks|Standard deviation of glucose levels as a measure of glucose variability, Defined as per CGM data, in mmol/L, 4 weeks|Percentage coefficient of variation of glucose levels, % as per CGM data, 4 weeks|Proportion of participants with TIR between 3.9 - 10.0 mol/L ≥ 70%, As per CGM data, 4 weeks|Glycated hemoglobin, Blood test to assess control within last 3-4 months, 15 weeks|Average scores between interventions based on quality of life questionnaires, These include: Type 1 Diabetes Distress Scale, Hypoglycemic Fear Survey - II, INSPIRE questionnaire for adults, Diabetes Bowel Syndrome Questionnaire, Diabetes Treatment Satisfaction Questionnaire, 15 weeks|Blood pressure and heart rate, Body measurements as described (mmHg and beats per minutes), 15 weeks|Measured of body mass: weight, body mass index, waist circumference, hip circumference, waist-to-hip ratio, Measurements done at visit - weight in kilograms, body mass index as per kg/m\^2, circumferences in cm, 15 weeks|Lipid profile, specifically: LDL-cholesterol, HDL-cholesterol, triglycerides, Blood tests, in mmol/L, 15 weeks|Biochemical analyses (exploratory), CRP, ferritin, IL-6, Brain natriuretic peptide, TXNIP, 15 weeks|Urine albumin-creatinine ratio, Urine test, 15 weeks|Glucagon, C-peptide, Paracetamol absorption after mixed meal tolerance test (in first 15 participants), Test done where beverage given and subsequent blood tests done after., 15 weeks
|