Artificial Pancreas Control System in an Inpatient Setting

Inclusion Criteria: * Diagnosis of type 1 diabetes mellitus for at least 1 year. * Male or female subjects 21 to 65 years of age. * Current use of an insulin pump. * Willingness to follow all study procedures, including attending all clinic visits. * Willingness to sign informed consent and HIPAA documents. Exclusion Criteria: * Pregnancy or Lactation: For women of childbearing potential: there is a requirement for a negative urine pregnancy test and for agreement to use contraception during the study and for at least 1 month after participating in the study. 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. * Renal insufficiency (serum creatinine of 2.0 mg/dL or greater). * Serum ALT or AST equal to or greater than 3 times the upper limit of normal; hepatic synthetic insufficiency as defined as a serum albumin of less than 3.3 g/dL; or serum bilirubin of over 2. * Adrenal insufficiency * Hematocrit of less than or equal to 34%. * A history of cerebrovascular disease or coronary artery disease regardless of the time since occurrence. * Congestive heart failure, NYHA class III or IV. * Diagnosis of 2nd or 3rd degree heart block or any arrhythmia judged by the investigator to be exclusionary. * Any active infection. * Visual impairment preventing reading of glucose meter values or continuous glucose monitoring device. * Physical impairment impeding the ability to use a glucose meter or glucose monitoring device. * Active foot ulceration. * Severe peripheral arterial disease characterized by ischemic rest pain or severe claudication. * Active alcohol abuse, substance abuse, or severe mental illness (as judged by the principal investigator). * Active malignancy, except basal cell or squamous cell skin cancers. * Major surgical operation within 30 days prior to screening. * Seizure disorder. * Chronic usage of any immunosuppressive medication (such as cyclosporine, azathioprine, sirolimus, or tacrolimus). * Current administration of oral or parenteral corticosteroids. * Use of an investigational drug within 30 days prior to screening. * Bleeding disorder, treatment with warfarin, or platelet count below 50,000. * Allergy to aspart insulin. * Allergy to glucagon. * Past history of pheochromocytoma or a family history of MEN 2, neurofibromatosis, or von Hippel-Lindau disease. * Insulin resistance requiring more than 200 units per day. * Need for uninterrupted treatment of acetaminophen. * Intolerance of mild hypoglycemia (glucose 60-70 mg/dl). * History of hypoglycemic unawareness. * Insulin antibody level of ≥ 100 µUnits/ml. * C peptide level of ≥0.5 ng/ml. * Any concurrent illness, other than diabetes, that is not controlled by a stable therapeutic regimen. * Any reason the principal investigator deems exclusionary