Patient description: The patient is a 24-year-old man who has had type 1 diabetes for 11 years. He presents to the emergency room with hyperglycemia and concern for possible diabetic ketoacidosis after not taking his insulin for 3 days. The patient reports that he is currently homeless and has lost his supply of insulin, syringes, glucometer, and glucose testing supplies. The patient states that at the time of his initial diagnosis with type 1 diabetes he was hospitalized with a glucose value >1000 mg/dL. At the time, he was experiencing polyuria, polydipsia, and polyphagia. He reports that he has been on insulin since the time of his diagnosis, and he has never been prescribed oral agents for diabetes management. Most recently, he has been using insulin glargine 55 units once daily, and insulin aspart sliding scale 3 times daily. The patient has had previous episodes of diabetic ketoacidosis, for which he was hospitalized. With this episode of hyperglycemia, he is not experiencing any nausea, vomiting, or abdominal discomfort, and he appears well. His lab studies showed: A1c: 11.3% Creatinine: 0.9 mg/dL with eGFR >60 mL/min Aspartate aminotransferase (AST): 17 U/L Alanine aminotransferase (ALT): 14 U/L Beta-hydroxybutyrate: 0.1 mmol/L Bicarbonate: 25 mEq/L Anion

Clinical trial eligibility criteria: eligible ages (years): 14.0-30.0,  Type 1 Diabetes Mellitus Type 1 diabetes mellitus (as diagnosed clinically) for at least one year 2. Age 14-<30 years at enrollment 3. For females, not currently known to be pregnant, be breast-feeding or planning to become pregnant within the study duration. 4. Using an insulin pump or multiple daily injections of insulin 1. Participant must be able to obtain U-100 rapid acting insulin analogues, Aspart or Lispro, for use during the study (since these are the only insulins approved for the study pump and the study is not supplying insulin) 2. MDI users must be on a basal/bolus regimen 3. Participants must have a minimum total daily dose (TDD) of at least eight units 5. HbA1c from an approved HbA1c point of care analyzer with a value 7.0%-11.0% 6. Willingness or ability to do carbohydrate counting 7. In the investigator's judgment, able to understand and likely to be adherent to the protocol 8. For subjects <18 years old, living with one or more diabetes care partners (eg.g. parent/legal guardian), of whom at least one is committed to participating in study training for emergency procedures for severe hypoglycemia and able to contact the participant in case of an emergency. 9. Have adequate internet access and a computer system that meets requirements for uploading data. 10. For participants currently using CGM or insulin pump, willingness to discontinue personal CGM and pump when using the study CGM and pumps (note: including implantable CGMs)  Individuals meeting any of the following at screening will be excluded from study participation: 1. Concomitant disease that influences metabolic control or HbA1c interpretation (e.g. anemia, significantly impaired hepatic function, confirmed gastroparesis, renal failure, history of adrenal insufficiency, sickle cell disease, haemoglobinopathy, or has received red blood cell transfusion or erythropoietin within three months prior to time of screening) or other medical condition which, in the Investigator's opinion, may compromise patient safety, affect outcome assessments, or affect the participant's ability to follow the protocol 2. Oral or parenteral glucocorticoids taken within 1 month prior to enrollment, or plans to take oral or parenteral glucocorticoids within the planned study duration. Exceptions: Short term oral or parenteral glucocorticoids up to seven days 3. Use of antidiabetic agents other than insulin 4. Use of other medications, which in the judgment of the investigator would be a contraindication to participation in the study 5. One or more episodes of severe hypoglycemia (hypoglycemia requiring treatment by another person) within the previous six months 6. Known allergy to medical grade adhesives 7. Participation in another study of a medical device or drug that could affect glucose measurements or glucose management or receipt of any investigational medical product within 1 month prior to enrollment 8. Current eating disorder such as anorexia or bulimia 9. Currently abusing illicit drugs, marijuana, prescription drugs, or alcohol 10. Visual impairment or hearing loss, which may compromise the participant's ability to perform all study procedures safely, as determined by the investigator 11. One or more episodes of diabetic ketoacidosis (DKA) requiring hospitalization within six months prior to screening 12. Working night shifts 13. Untreated celiac disease, hyperthyroidism, or hypothyroidism 14. Clinically significant nephropathy (eGFR <45 mL/min) or on dialysis. Creatinine to determine eGFR must have been obtained as part of usual care within 12 months prior to enrollment (if not available, at time of enrollment, screening can proceed but it must be available prior to randomization)