Inclusion Criteria:
* Age 18 to 80 years old inclusive
* Generally in good health, as determined by the investigator
* Living in the United States with no plans to move outside the United States during the study
* Diagnosis of T1D for at least 12 months
* Currently using a Tandem pump
* Current Dexcom CGM user
* HbA1c \<9.0% in the last 6 months.
* Willing to implement and adhere to pump alert/alarm settings on a study-provided pump as instructed during the study
* Willing to wear each investigational infusion set for up to 7 days during each of the wear periods in the study
* Willing to perform blood ketone and blood glucose (fingerstick) measurements as directed using provided ketone and blood glucose meters and strips
* If using Tandem Mobi, has a compatible cellular phone that can run the Tandem Mobi Mobile App
* BMI in the range 18-35 kg/m2, both inclusive
* Currently using one of the following insulins with no expectation of a need to change insulin type during the study:
1. Humalog™ (or generic insulin lispro)
2. NovoLog™ (or generic insulin aspart)
* Willing to change insulin cartridge every 48-72 hours, as recommended by patient's healthcare provider during the study
* Has the ability to understand and comply with protocol procedures and to provide informed consent
Exclusion Criteria:
* Concurrent use of any non-insulin glucose-lowering agent, other than metformin (for example, GLP-1 agonists, Symlin, DPP-4 inhibitors, SGLT-2 inhibitors, sulfonylureas)
* Female subject is pregnant, planning to become pregnant, or not using adequate method of contraception
* Episodes of severe hypoglycemia in the last 6 months resulting in:
1. Medical Assistance (i.e., paramedics, hospital evaluation or hospitalization)
2. Loss of consciousness
3. Seizures
* One or more episodes of diabetic ketoacidosis (DKA) in the last 6 months requiring hospitalization
* Currently on a ketogenic or low-carbohydrate diet of less than 60 grams of carbohydrates per day, or intending to begin one during the study period
* Known history of any of the following conditions:
1. Cushing's Disease
2. Adrenal insufficiency
3. Pancreatic islet cell tumor
4. Insulinoma
5. Lipodystrophy
6. Extensive lipohypertrophy, as assessed by the investigator
* Undergoing treatment with systemic oral or intravenous corticosteroids, at or within the last 8 weeks from screening. Inhaled glucocorticoids are allowed.
* Significant history of any of the following, that in the opinion of the investigator would compromise safety or successful study participation:
1. Alcoholism
2. Drug abuse
* Significant acute or chronic illness, that in the opinion of the investigator might interfere with safety or integrity of study results
* Current participation in another clinical drug or device study
* Immediate family member (spouse, biological or legal guardian, child, sibling, parent) who is a study site personnel directly affiliated with this study or who is an employee of Tandem Diabetes Care
