This clinical trial is a safety and feasibility study to assess the performance of artificial pancreas (AP) system using the Zone Model Predictive control (Zone-MPC) and Health Monitoring System (HMS) algorithms embedded into the APS APP platform.

The system will be evaluated on up to 10 adult subjects with type 1 diabetes age 18-75 years old at a single clinical site (Sansum Diabetes Research Institute), who will complete a 48-hour closed-loop (CL) session in an observed CRC environment with medical staff present. During the session subjects will bolus for all meals and snacks and perform a 45-minute walking session while supervised by medical staff. The AP system used consists of an insulin pump, a CGM sensor, and a phone app (the Artificial Pancreas System [APS] phone app).

Inclusion Criteria:

• Age ≥ 18 and ≤ 75 years at the time of screening.
• Clinical diagnosis of type 1 diabetes for at least one year.
• Has been using an insulin pump for at least 6 months at the time of screening.
• HbA1c < 10.5%.
• Bolus for all meals and snacks that contain ≥ 5 grams of carbohydrate.
• Willing to perform at least 7 fingerstick blood glucose tests a day.
• If using Apidra (insulin glulisine) at home and planning to use the Tandem t:AP pump for the closed-loop session, willing to switch to Novolog or Humalog for the closed-loop session.
• Willing to refrain from taking acetaminophen products for the duration of the clinical trial.
• Willing to abide by the study protocol and use study-provided devices, including the Omnipod OR Tandem Pump, Dexcom CGM, glucometer, ketone meter and APS APP on the study phone device.

Exclusion Criteria:

• Pregnancy
• One or more episodes of hypoglycemia requiring an emergency room visit or hospitalization in the past 6 months.
• One or more episodes of hyperglycemia requiring an emergency room visit or hospitalization in the past 6 months.
• Known unstable cardiac disease or untreated cardiac disease, as revealed by history or physical examination.
• Dermatological conditions that would preclude wearing a CGM sensor or Pod/infusion site.
• One or more seizures in the past year.
• Any condition that could interfere with participating in the trial, based on investigator judgment.
• Participation in another pharmaceutical or device trial at the time of enrollment or during the study.