NO-Meal Announcement in Automated Insulin Delivery (Open-source and Commercial) Systems (NOMAD)

Inclusion Criteria:

• Males and females ≥ 18 years old currently residing in Canada or the United States of America (USA)
• Having a clinical diagnosis of T1D for at least one year (based on the investigator's judgment; C peptide level and antibody determinations are not needed.)
• Having been on OS-AID therapy for at least 2 weeks and using a Dexcom G6 or G7 CGM.
• If using an ultra-rapid acting insulin, be willing to switch to a rapid-acting insulin, as the former are not recommended in the C-AID systems used in the study (due to the risk of cannula or pod blockage).
• Accepting that personal pump setting parameters will be collected by the research team. This access will be limited to the study period.

Exclusion Criteria:

• Using regular insulin (Novolin ge Toronto or Humulin R) or U200 or U500 concentrated insulin (e.g. Humalog U200, Entuzity U500)
• Participant-reported clinically significant nephropathy (eGFR < 25 ml/min/1.73m2, planned or on dialysis), neuropathy (e.g., known uncontrolled gastroparesis) or retinopathy (e.g., proliferative retinopathy with ongoing active treatment such as laser photocoagulation or planned surgery) as judged by the investigator
• Recent (<3 months) acute macrovascular event (e.g., acute coronary syndrome or cardiac surgery)
• Anticipated therapeutic change (including change of CGM sensor [other than Dexcom sensors] or AID system type, new antidiabetic drug initiation) between admission and end of the study
• % of time spent out of automated mode exceeding 10% in last month's trial start
• Anticipated need to use hydroxyurea during the study period (as it can interfere with CGM readings)
• Pregnancy (ongoing or current attempt to become pregnant)
• Breastfeeding
• Plan to go abroad in a foreign country during the study period
• Severe hypoglycemic episode within one month of screening
• Severe hyperglycemic episode (including DKA) requiring hospitalization in the last 3 months
• Current use of glucocorticoid medication (except low stable dose and inhaled steroids and stable adrenal insufficiency treatment e.g., Cortef®)
• Current use of SGLT-2 inhibitors or GLP1 agonists or other antidiabetic agents (Metformin, DPP-4 inhibitors) unless at a stable dose for at least 3 months, without anticipated change during the study and appropriate ketone testing is performed (for iSGLT2 treatment).
• Known or suspected allergies to study products (e.g., Dexcom adhesive)
• Other serious medical illnesses likely to interfere with study participation or with the ability to complete the study by the judgment of the investigator
• Anticipation of a significant change in exercise or diet regimen between admission and end of the study (i.e., starting or stopping an organized sport; planned significant diet change)
• Anticipated radiologic examination at the time of study assessment incompatible with CGM wear (e.g., MRI)
• In the opinion of the investigator, a participant who is unable or unwilling to observe the contraindications of the study device.