Inclusion Criteria:

• Age 18-65 years
• BMI 19-40 kg/m2
• Creatinine ≤ 1.5 mg/dl or eGFR of >50 ml/min
• no acute or chronic disease
• current non-smoker
• alcohol consumption <5 g/week
• for women of child bearing potential, negative pregnancy test
• no eating disorder
• no current substance abuse
• no history of chest pain or shortness of breath at rest or on exertion.
• HbA1c ≤ 10%
• On insulin pump therapy for at least six months
• no symptomatic gastroparesis
• no unstable retinopathy (requiring photocoagulation within past 6 months)
• no unstable macrovascular disease (requiring interventions within past 12 months)
• no orthopedic problems that would preclude exercise trials proposed
• Currently using insulin-to-carbohydrate ratio to calculate meal bolus sizes
• An understanding of and willingness to follow the protocol and sign the informed consent
• No GI problems as per the GI symptom questionnaire
• Willing to switch own insulin pump to Tandem pump for the study

Exclusion Criteria:

• Admission for diabetic ketoacidosis in the 12 months prior to enrollment
• Severe hypoglycemia resulting in seizure or loss of consciousness in the 12 months prior to enrollment
• History of a seizure disorder (except hypoglycemic seizure), unless written clearance is received from a neurologist
• Coronary artery disease or heart failure, unless written clearance is received from a cardiologist
• History of cardiac arrhythmia (except for benign premature atrial contractions and benign premature ventricular contractions which are permitted)
• Cystic fibrosis
• A known medical condition that in the judgment of the investigator might interfere with the completion of the protocol such as the following examples:
  • Inpatient psychiatric treatment in the past 6 months for either the subject or the subject’s primary care giver (i.e., parent or guardian)
  • Presence of a known adrenal disorder
  • Abnormal liver function test results (ALT >2 times the upper limit of normal).
  • Abnormal renal function test results (creatinine >1.4 in women and >1.5 in men)
  • Active gastroparesis
  • 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 (TSH undetectable or >10 mlU/L); testing required within three months prior to admission for subjects with a goiter or who are on thyroid hormone replacement, and within one year otherwise
  • Abuse of alcohol or recreational drugs
  • Infectious process not anticipated to resolve prior to study procedures (e.g. meningitis, pneumonia, osteomyelitis)
• A recent injury to body or limb, muscular disorder, use of any medication, any carcinogenic disease, or other significant medical disorder if that injury, medication or disease in the judgment of the investigator will affect the completion of the protocol
• Current use of the following drugs and supplements:
  • Acetaminophen
  • Any medication being taken to lower blood glucose, such as Pramlintide, Metformin, GLP-1 Analogs such as Liraglutide, and nutraceuticals intended to lower blood glucose
  • Oral or injectable glucocorticoids
  • Medications known to affect gastric emptying (e.g., erythromycin)
  • Any other medication that the investigator believes is a contraindication to the subject’s participation