Two Way Crossover Closed Loop MPC vs Control IQ

Participants will undergo one 7-day Intervention Period and one 7-day Control Period in randomized order. During the 7-day intervention, participants will wear an Omnipod to deliver Fiasp insulin and a Dexcom G6 CGM. The CGM system will provide sensed glucose data every 5 minutes. Sensor glucose data will be wirelessly transmitted via Bluetooth Low Energy (BTLE) from the Dexcom G6 to the smartphone master controller every 5 minutes. The smartphone will communicate via BTLE to an Omnipod for insulin delivery. The closed loop system will receive activity data through a Polar M600 watch worn by the participant. Participants will eat one meal in clinic and complete system training on Day 1 and then spend the rest of the 7 days at home. During the 7-day control, the participant will continue their usual diabetes care regimen using the tslim X2 pump with Dexcom G6 with Control IQ enabled.

Inclusion criteria

• Diagnosis of type 1 diabetes mellitus for at least 1 year.
• Age 18 years and older.
• Current use of a t:slim X2 insulin pump with Dexcom G6 with the use of Control IQ for at least 12 weeks.
• Willingness to use Fiasp insulin during intervention study
• Lives with another person age 18 or older who will sleep in the house at night and that can attend the training on using the system.
• Lives within 40 miles of enrollment site.
• HbA1c ≥ 7.5% at screening.
• Total daily insulin requirement is less than 139 units/day.
• Current use of a smartphone so can be contacted by study staff off-campus
• Willingness to follow all study procedures, including attending all clinic visits.
• Willingness to sign informed consent and HIPAA documents.

Exclusion criteria

• Female of childbearing potential who is pregnant or intending to become pregnant or breast-feeding, or is not using adequate contraceptive methods. Acceptable contraception includes birth control pill / patch / vaginal ring, Depo-Provera, Norplant, an IUD, the double barrier method (the woman uses a diaphragm and spermicide and the man uses a condom), or abstinence.
• HbA1c >10% at screening.
• Any cardiovascular disease, defined as a clinically significant EKG abnormality at the time of screening or any history of: stroke, heart failure, myocardial infarction, angina pectoris, or coronary arterial bypass graft or angioplasty. Diagnosis of 2nd or 3rd degree heart block or any non-physiological arrhythmia judged by the investigator to be exclusionary.
• Renal insufficiency (GFR < 60 ml/min, using the MDRD equation as reported by the site laboratory).
• Liver failure, cirrhosis, or any other liver disease that compromises liver function as determined by the investigator.
• History of severe hypoglycemia during the past 12 months prior to screening visit or hypoglycemia unawareness as judged by the investigator. Participants will complete a hypoglycemia awareness questionnaire. Participants will be excluded for four or more R responses.
• History of diabetes ketoacidosis during the prior 6 months prior to screening visit, as diagnosed on hospital admission or as judged by the investigator.
• Adrenal insufficiency.
• Any active infection.
• Known or suspected abuse of alcohol, narcotics, or illicit drugs.
• Seizure disorder.
• Active foot ulceration.
• Severe peripheral arterial disease characterized by ischemic rest pain or severe claudication.
• Major surgical operation within 30 days prior to screening.
• Use of an investigational drug within 30 days prior to screening.
• Chronic usage of any immunosuppressive medication (such as cyclosporine, azathioprine, sirolimus, or tacrolimus).
• Bleeding disorder, treatment with warfarin, or platelet count below 50,000.
• Allergy to Fiasp insulin.
• Current administration of oral or parenteral corticosteroids.
• Any life-threatening disease, including malignant neoplasms and medical history of malignant neoplasms within the past 5 years prior to screening (except basal and squamous cell skin cancer).
• Current use of beta blockers or non-dihydropyridine calcium channel blockers.
• Current use of any medication intended to lower glucose other than insulin (ex. use of metformin or liraglutide).
• Gastroparesis
• Low carbohydrate diet at the time of screening defines as less than 50 grams of carbohydrate per day.
• Any clinically significant disease or disorder which in the opinion of the Investigator may jeopardize the participant's safety or compliance with the protocol.