"FEXIS": (Feasibility of an Extended Wear CSII Set in Participants With T1DM)

Inclusion Criteria: 1. Participant is 18 - 70 years of age inclusive 2. Participant is in generally good health, as determined by the investigator 3. Participant is willing and able to individually complete written informed consent and agrees to comply with all study related testing and examinations 4. Participant must be geographically stable (e.g., expects to be available and capable of returning for all study specified test and examinations) during the study period 5. Participant has been diagnosed with T1DM for at least 12 months 6. C-peptide less than 0.6 nmol per L at screening 7. Subject can provide a minimum of 14 days of insulin pump data to demonstrate pump use compliance 8. Participant is willing to perform serum ketone measurements whenever the blood glucose is determined to be greater than 250 mg per dL (14 mmol per L) using a ketone meter and strips provided by the sponsor 9. Participant has BMI in the range 20 - 35 kg per square metre inclusive 10. Participant has experience infusing a rapid-acting insulin analog for at least 6 months 11. Participant has been using an insulin pump with commercially available infusion sets for at least 6 months (this includes Automated Insulin Delivery systems) 12. Participant has previous experience using a continuous glucose monitor (CGM) and is willing to use a CGM for the duration of the study and perform necessary calibration fingerstick glucose readings 13. Participant has ability to understand and comply with protocol procedures and to provide informed consent 14. AST and ALT less than or equal to 120 U per L 15. Creatinine less than 1.8 mg per dL Exclusion Criteria: 1. Participants whose average total daily insulin dose exceeds 85 units per day (i.e. typically change insulin reservoirs more often than every 3.5 days on average) 2. Participants who routinely change their commercial insulin infusion sets twice weekly or less often (wear time greater than 3.5 days) 3. Female participant is pregnant or nursing (Documented negative pregnancy test results for female participants required unless participant is menopausal without any spontaneous menstrual cycles for \>12 months or key organs have been removed.) 4. Participant has abnormal skin at intended device infusion sites (existing infection, inflammation, burns, or other extensive scarring) 5. Participant has HbA1C greater than 8.5 percent at screening 6. Participant has documented history in last 6 months of severe hypoglycemia associated with cognitive dysfunction sufficiently severe to require third party intervention or a history of impaired awareness of hypoglycemia. 7. Participant has a history of diabetic ketoacidosis in the last 6 months 8. Participant has known cardiovascular disease considered to be clinically relevant by the investigator 9. Participant has known arrhythmias considered to be clinically relevant by the investigator 10. Participant has known history of: 1. Cushing's Disease, 2. pancreatic islet cell tumor, or 3. insulinoma 11. Participant has: 1. Lipodystrophy, 2. extensive lipohypertrophy, as assessed by the investigator 12. Participant is undergoing current treatment with: 1. Systemic oral or intravenous corticosteroids, 2. monoamine oxidase (MAO) inhibitors, 3. non-selective beta-blockers, 4. growth hormone, 5. thyroid hormones, unless use has been stable during the past 3 months 13. Subject has significant history of any of the following, that in the opinion of the investigator would compromise the subject's safety or successful study participation: 1. Alcoholism, 2. drug abuse 14. Significant acute or chronic illness, that in the investigator's opinion, might interfere with subject safety or integrity of study results 15. Planned operation, MRI or CT which require removal of infusion set or CGM sensor during wear periods 16. Current participation in another clinical drug or device study 17. AST and ALT greater than 120 U per L 18. Creatinine equal to or greater than 1.8 mg per dL -