Outpatient Control-to-Range: System and Monitoring Testing

Inclusion Criteria: 1. ≥21 and \<65 years old 2. Clinical diagnosis of type 1 diabetes mellitus: Criteria for documented hyperglycemia (at least 1 criterion must be met): * Fasting glucose ≥126 mg/dL - confirmed * Two-hour OGTT glucose ≥200 mg/dL - confirmed * HbA1c ≥6.5% documented by history - 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 (at least 1 criterion 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 3. Use of an insulin pump to treat his/her diabetes for at least 1 year 4. Actively using an insulin pump with bolus calculator feature including predefined parameters for carbohydrate ratio, insulin sensitivity factor, target BG and active insulin. 5. HbA1c between 6.0% - 9.0% as measured with DCA2000 or equivalent device 6. Not currently known to be pregnant, breast feeding, or intending to become pregnant (females) 7. Demonstration of proper mental status and cognition for the study 8. Willingness to avoid consumption of acetaminophen-containing products during the study interventions involving DexCom use 9. If on antihypertensive, thyroid, anti-depressant or lipid lowering medication, have stability on the medication for at least 2 months prior to enrollment in the study Exclusion Criteria: 1. ≥21 and \<65 years old 2. Clinical diagnosis of type 1 diabetes mellitus: * Criteria for documented hyperglycemia (at least 1 criterion must be met): * Fasting glucose ≥126 mg/dL - confirmed * Two-hour OGTT glucose ≥200 mg/dL - confirmed * HbA1c ≥6.5% documented by history - 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 (at least 1 criterion 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 3. Use of an insulin pump to treat his/her diabetes for at least 1 year 4. Actively using an insulin pump with bolus calculator feature including predefined parameters for carbohydrate ratio, insulin sensitivity factor, target BG and active insulin. 5. HbA1c between 6.0% - 9.0% as measured with DCA2000 or equivalent device 6. Not currently known to be pregnant, breast feeding, or intending to become pregnant (females) 7. Demonstration of proper mental status and cognition for the study 8. Willingness to avoid consumption of acetaminophen-containing products during the study interventions involving DexCom use 9. If on antihypertensive, thyroid, anti-depressant or lipid lowering medication, have stability on the medication for at least 2 months prior to enrollment in the study