Evaluation of Fiasp® (Fast Acting Insulin Aspart) in 670G Hybrid Closed-Loop Therapy

Inclusion Criteria: 1. Clinical diagnosis of type 1 diabetes and using 670G pump for at least 1 month, and willing to have the 670G pump downloaded into a Carelink Clinical research database. 2. The diagnosis of type 1 diabetes is based on the investigator's judgment; C-peptide level and antibody determinations are not needed. 3. Age ≥18 years 4. Using Novolog or Fiasp® insulin at time of enrollment 5. Willing to use Fiasp® insulin 6. Total daily insulin dose is at least 0.3 units/kg/day 7. Usual carbohydrate intake is at least 60 grams a day, and willing to have at least 25 grams of carbohydrates for breakfast 8. For females, not currently known to be pregnant 9. An understanding of and willingness to follow the protocol and sign the informed consent 10. Willing to have photographs taken of their infusion sites 11. Willing to download their 670G pump every 1-2 weeks to a research Carelink account 12. Willingness to answer a brief online questionnaire every 2 weeks 13. Must be able to understand spoken or written English 14. For subjects participating in Part 2 of this study they will need to be using Fiasp® as part of their usual care 15. Hemoglobin A1c between 6 and 10% at the time of enrollment Exclusion Criteria: 1. Pregnant or lactating females 2. No hypoglycemic seizure or loss of consciousness in the past 6 months 3. Severe episode of DKA in the 6 months prior to study enrollment that was unrelated to an infusion set failure 4. No known cardiovascular events in the last 6 months 5. No active proliferative diabetic retinopathy 6. Known tape allergies 7. Current treatment for a seizure disorder 8. Cystic fibrosis 9. Active infection 10. A known medical condition that in the judgment of the investigator might interfere with the completion of the protocol 11. Inpatient psychiatric treatment in the past 6 months 12. Presence of a known adrenal disorder 13. If on antihypertensive, thyroid, anti-depressant or lipid lowering medication, with lack of stability on the medication for the past 2 months prior to enrollment in the study 14. Abuse of alcohol 15. Dialysis or renal failure 16. Known eGFR \<60% Note: Adequately treated thyroid disease and celiac disease do not exclude subjects from enrollment.