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): 14.0-75.0,  Type 1 Diabetes Subject is 14-75 years of age at time of screening 2. Subject has a clinical diagnosis of type 1 diabetes, as determined via medical record or source documentation by an individual qualified to make a medical diagnosis that are Based on Demands of In-Clinic Study Procedures 3. On pump therapy at the time of screening with insulin sensitivity and insulin carbohydrate ratio 4. Adequate venous access as assessed by investigator or appropriate staff  that are Based on Demands of In-Clinic Study Procedures 1. Subject is unable to tolerate tape adhesive in the area of sensor placement 2. Subject has any unresolved adverse skin condition in the area of sensor or device placement (e.g., psoriasis, rash, Staphylococcus infection) 3. Subject is actively participating in an investigational study (drug or device) wherein they have received treatment from an investigational study (drug or device) in the last 2 weeks 4. Subject has a positive urine or serum pregnancy screening test 5. Subject is female, sexually active without use of contraception and plans to become pregnant during the course of the study 6. Subject has had a hypoglycemic induced seizure within the past 6 months prior to screening visit 7. Subject has had hypoglycemia resulting in loss of consciousness within the past 6 months prior to screening visit 8. Subject has had an episode of diabetic ketoacidosis (DKA) within the past 6 months prior to screening visit 9. Subject has a history of a seizure disorder 10. Subject has central nervous system or cardiac disorder resulting in syncope 11. Subject has a history of myocardial infarction, unstable angina, coronary artery bypass surgery, coronary artery stenting, transient ischemic attack (TIA), cerebrovascular accident (CVA), angina, congestive heart failure, ventricular rhythm disturbances or thromboembolic disease 12. Subjects with hematocrit (Hct) lower than the normal reference range for age per local lab testing 13. Subjects with a history or findings on screening electrocardiogram (EKG) of any cardiac arrhythmia, including atrial arrhythmias 14. Subjects with a history of adrenal insufficiency 15. Subjects with history of migraines that have occurred at least 2 times in the last 3 months prior to enrollment