CGMIS 48-hour Feasibility Study

Inclusion Criteria: * Type 1 diabetes, present for at least 6 months. If there is lack of clarity regarding the type of diabetes, the PI will make the final decision based on medical records. * Age 18-75 * Currently using a Tandem T-Slim or Medtronic 523/723 or newer series insulin pump to treat their diabetes. * Hgb A1C between 5.8 and 10% * Willingness to follow all study procedures and to attend all clinic visits. * Willingness to sign informed consent and HIPPA documents. Exclusion Criteria: * Need for MRI/CT/Diathermy during study participation * Current use of Hydroxyurea * History of chronic kidney disease * Inability to read pump or CGM display due to reduced visual acuity * History of unstable ischaemic heart disease or myocardial infarction within the last 3 months. * History of chronic liver disease * Active infection such as HIV or hepatitis * Anemia defined by HCT at least 4 percentage points below lower limit of the reference range * Dementia, Schizophrenia or other untreated mental illness * Chronic substance abuse * Chronic alcohol abuse * Seizure disorder * Major surgical operation within 30 days prior to screening * History of bleeding disorder or treatment with anticoagulants. * Allergy to acrylate-based skin adhesives * Ongoing use of an investigational drug or device * Female of childbearing potential who is pregnant or intending to become pregnant * Diabetic ketoacidosis or hypoglycemia requiring hospitalization within the last 6 months * Insulin resistance as defined by insulin requirement of more than 200 units per day * Use of glucose-lowering medications other than insulin * Need for uninterrupted treatment with acetaminophen * Any other physical or mental condition judged by the PI as being exclusionary.