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): 21.0-64.0,  Type 1 Diabetes Mellitus Type I diabetes mellitus (TIDM) (as defined by the American Diabetes Association or judgment of a physician) for at least two years prior to the enrollment in the study Use of an insulin pump to treat their diabetes for at least six months prior to the study Ability to use a bolus calculator function with the current insulin pump with pre-defined parameters for glucose goal, carbohydrate ratio, and insulin sensitivity factor Age 21 years. Adults age 65 and over are likely to have medical exclusions for the follow-up Phase 2 study, which involves induced hypoglycemia Completed Phase 1 of the Institutional Review Board (IRB) #14956 "Development of a Behavioral Observer for Type 1 Diabetes Mellitus" Willingness to use lispro (Humalog) insulin two days prior to and during inpatient admission Willingness to perform Self-Monitoring Blood Glucose (SMBG) 4 times per day at times before meals and bedtime Demonstration of proper mental status and cognition for completion of the study  Pregnancy Psychiatric disorders that would interfere with study tasks (e.g. mental retardation, substance abuse) History of a systemic deep tissue infection with methicillin-resistant staph aureus or Candida albicans Known bleeding diathesis or dyscrasia Active enrollment in another clinical trial Medical condition that would make operating an insulin pump difficult (e.g. blindness, severe arthritis, extensive scar tissue at sites where devices are inserted) Anemia (hematocrit <36% [females], <38% [males]) Allergy or adverse reaction to lispro (Humalog) insulin Conditions which may increase the risk of induced hypoglycemia such as symptomatic heart disease, congestive heart failure, history of a cerebrovascular event, atrial fibrillation, renal insufficiency (creatinine >1.5) or uncontrolled hypertension (resting blood pressure >140/90)