Pilot Study 1 of Outpatient Control-to-Range - System and Monitoring Testing

Inclusion Criteria: * Patient must be aged between 21 (inclusive) and 65 years old. The age of 21 has been chosen because this trial is supported by a US Foundation. * Patient must have been clinically diagnosed with Type 1 diabetes mellitus. For an individual to be enrolled at least one criterion from each list must be met: * Criteria for documented hyperglycemia (at least 1 must be met): * Fasting glucose ≥126 mg/dL - confirmed * Two-hour OGTT glucose ≥200 mg/dL - confirmed * HbA1c ≥6.5% documented - confirmed * Random glucose ≥200 mg/dL with symptoms * No data at diagnosis is available but the participant has a convincing history of hyperglycemia consistent with diabetes * Criteria for requiring insulin at diagnosis (1 must be met): * Participant required insulin at diagnosis and continually thereafter * Participant did not start insulin at diagnosis but upon investigator review likely needed insulin (significant hyperglycemia that did not respond to oral agents) and did require insulin eventually and used continually * Participant did not start insulin at diagnosis but continued to be hyperglycemic, had positive islet cell antibodies - consistent with latent autoimmune diabetes in adults (LADA) and did require insulin eventually and used continually * Use of an insulin pump to treat his/her diabetes for at least 1 year * Actively using a carbohydrate \[CHO\] / insulin ratio for insulin bolus adjustments in order to keep blood glucose in a predefined range * Patient HbA1c is between 6.0% and 9% as measured with DCA2000 or equivalent device * Patient must demonstrate proper mental status and cognition for the study * Patient must be willing to avoid consumption of acetaminophen-containing products during the study interventions involving DexCom use * Patient must be affiliated or beneficiary of a social medical insurance * Patient has signed informed consent form prior to study entry Exclusion Criteria: * Diabetic ketoacidosis within the 6 months prior to enrollment * Severe hypoglycemia resulting in seizure or loss of consciousness in the 12 months prior to enrollment * Pregnancy, breast feeding, or intention of becoming pregnant * Uncontrolled arterial hypertension (diastolic blood pressure \>90 mmHg and/or systolic blood pressure \>160 mmHg) * Conditions which may increase the risk of hypoglycemia such as uncontrolled coronary artery disease during the previous year (e.g. history of myocardial infarction, acute coronary syndrome, therapeutic coronary intervention, coronary bypass or stenting procedure, stable or unstable angina, episode of chest pain of cardiac etiology with documented EKG changes, or positive stress test or catheterization with coronary blockages \>50%), congestive heart failure, history of cerebrovascular event, seizure disorder, syncope, adrenal insufficiency, neurologic disease or atrial fibrillation * History of a systemic or deep tissue infection with methicillin-resistant staph aureus or Candida albicans * Use of a device that may pose electromagnetic compatibility issues and/or radiofrequency interference with the DexCom CGM (implantable cardioverter-defibrillator, electronic pacemaker, neurostimulator, intrathecal pump, and cochlear implants) * Anticoagulant therapy other than aspirin * Oral steroids * Medical condition requiring use of an acetaminophen-containing medication that cannot be withheld for the study admissions. * Psychiatric disorders that would interfere with study tasks (e.g. inpatient psychiatric treatment within 6 months prior to enrollment) * Mental incapacity, unwillingness or language barriers precluding adequate understanding or cooperation * Known current or recent alcohol or drug abuse * Medical conditions that would make operating a CGM, cell phone, or insulin pump difficult (e.g. blindness, severe arthritis, immobility) * Any skin condition that prevents sensor or pump placement on the abdomen or arm (e.g. bad sunburn, pre-existing dermatitis, intertrigo, psoriasis, extensive scarring, cellulitis) * Impaired hepatic function measured as alanine aminotransferase or aspartate aminotransferase ≥three times the upper reference limit * Impaired renal function measured as creatinine \>1.2 times above the upper limit of normal * Uncontrolled microvascular (diabetic) complications (other than diabetic non-proliferative retinopathy), such as history of laser coagulation, proliferative diabetic retinopathy, known diabetic nephropathy (other than microalbuminuria with normal creatinine) or neuropathy requiring treatment * Active gastroparesis requiring current medical therapy * If on antihypertensive, thyroid, anti-depressant or lipid lowering medication, lack of stability on the medication for the past 2 months prior to enrollment in the study * Uncontrolled thyroid disease * Known bleeding diathesis or dyscrasia * Known allergy to medical adhesives, components of the insulin pump insertion set or continuous glucose monitor sensor * Unwillingness to withhold dietary supplements two weeks prior to admission and for the duration of the study participation. * Unwillingness to withhold pramlintide, liraglutide and exenatide for the duration of the study intervention. * Patient is actively enrolled in another clinical trial or was part of study within 30 days or whose annual study income is over 4 500€ * Persons deprived of freedom, adults protected by law or vulnerable persons