Visit 1: Screening Attend the clinical research unit Signed and dated informed consent Demographics data (date of birth, gender, race and ethnicity) Medical and surgical history and allergies to medication Details of the diabetes history Menstrual history and contraception (females) Medications and supplements Social history including drinking, smoking and drug habits Vital signs ECG Random venous blood and urine sample Urine pregnancy test in female participants of childbearing age Basic diabetes education revision, Insulin treatment adjusted if needed Questionnaires to be completed Participants will be provided with the real-time (RT) CGM (Dexcom) The participant will be instructed how to make correct CGM calibration. Quality control testing will be performed on the study devices as recommended in the manufacturer guidelines Participants will be shown how to insert the sensor themselves, interpret the CGM data in real time and to set the hypo- and hyperglycaemia threshold alarms. The alarm threshold will be set at 4mmol/l and 11mmol/l and participants will be encouraged to keep it at those levels and not to reduce the hypoglycaemia threshold below 3.3mmol/L) Participants to complete a 2-weeks run-in period using RT-CGM (Dexcom) and a standard bolus calculator to familiarize themselves with RT-CGM Participants on MDI will be provided with the study CBG meter Participants on CSII will be provided with the Cellnovo study