Biobehavioral Mechanisms of Glucose Variability

Inclusion Criteria: * Clinical diagnosis of type 1 diabetes mellitus for ≥2 years. 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 Blood Glucose (BG) ≥126 mg/dL * 2h Oral Glucose Tolerance Test (OGTT) ≥200 mg/dL * Hemoglobin (HbA1c) ≥6.5% * BG ≥200 mg/dL with symptoms * History of hyperglycemia consistent with diabetes * Criteria for requiring insulin at diagnosis (1 must be met): * required insulin at diagnosis and continually thereafter * no insulin at diagnosis but upon investigator review likely needed insulin (significant hyperglycemia that did not respond to oral agents) and insulin eventually required and used continually * no insulin at diagnosis but continued hyperglycemia, positive islet cell antibodies - consistent with latent autoimmune diabetes in adults (LADA) and insulin eventually required and used continually * Use of an insulin pump for at least six months prior to the study. * Using a bolus calculator with pre-defined parameters for carbohydrate ratio(s), and insulin sensitivity factor(s). * Signed informed consent. * Age ≥21 and \<65 years old. * HbA1c ≤10% as measured with DCA 2000 or equivalent device. * Willingness to use lispro (Humalog) insulin for metabolic challenge admission. * Willingness to perform self-monitoring blood glucose (SMBG) \>4 times/day. * Willingness to avoid consumption of acetaminop…