Glucagon Counterregulation in Type 1 Diabetes

Inclusion Criteria: * Clinical diagnosis, based on investigator assessment, of type 1 diabetes for at least 5 years and using insulin for at least 5 years * Use of an insulin pump for at least 6 months with established parameters for basal rate(s), carbohydrate ratio(s) and insulin sensitivity factor(s) for at least 3 months. * HbA1c level \<10.5% at screening * Demonstration of proper mental status and cognition for the study * Investigator has confidence that the subject can successfully operate all study devices and is capable of adhering to the protocol Exclusion Criteria: * Admission for diabetic ketoacidosis in the 6 months prior to enrollment. * Severe hypoglycemia resulting in seizure or loss of consciousness in the 3 months prior to enrollment. * Hematocrit less that the lower limit of normal for the assay. * Pregnancy, breast-feeding, or intention of becoming pregnant over time of study procedures * A known medical condition, which in the opinion of the investigator or designee, would put the participant or study at risk * 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 some drugs and supplements * Participation in another pharmaceutical or device trial at the time of enrollment or during the study * Basal insulin rates less than 0.01 units per hour * Diagnosed food allergies that would prohibit the consumption of a standardized meal * Any reason the study MD considers that the subject is not appropriate for the trial