A randomized, double-blinded (for insulin type), single centre, crossover design young adult study, on 20 subjects with type 1 diabetes (T1D), aged 18 to 25 (inclusive) years, measuring time in glucose values within 3.9 - 10 mmol/l (70-180 mg/dl) under supervision of DreaMed Glucositter using either faster-acting insulin Aspart (Fiasp®, European Medicines Agency number EMEA/H/C/004046) or normal acting insulin Aspart.

Study duration will be about 3 weeks per subject, 5 month overall.

The objectives of this clinical investigation is:

1. to evaluate the safety and efficacy of blood glucose control using the DreaMed Glucositter with Fiasp® in young adults with T1D during and after unannounced afternoon physical activity and unannounced meals, in a controlled in-hospital environment.

Primary endpoint is significant between-group difference (intervention Fast-CL versus control Regular-CL) in time within range of glucose values within 3.9 - 10 mmol/l (70-180 mg/dl) during the unannounced afternoon exercise and unannounced standardized meals from 15:00 till 18:00 next day based on sensor glucose readings.

Inclusion Criteria:

1. The subject has documented T1D, as defined by the American Diabetes Association and World Health Organization (ADA/WHO) for at least 1 year prior to study enrolment

2. Documented evidence should exist within the patient history of T1D

3. The subject is between 18 and 25 years of age (inclusive) at the time of enrolment

4. The subject has been treated with an insulin pump for at least 3 months

5. The subject has an A1C value ≤ 9% based on analysis from the local laboratory at the time of enrolment

   ● A1C testing must follow National Glycohemoglobin Standardization Program (NGSP) standards.

6. The subject is willing to follow all study instructions

7. Subject is available for the entire study duration and follow-up visits

8. Subject is willing to perform daily self-monitoring of blood glucose (SMBG) and required sensor calibrations

9. If subject has celiac/Hashimoto disease, the disease has to be adequately treated as determined by the investigator

10. Subject has a BMI above 5th centile and below 95th centile for age, respectively.

Exclusion Criteria:

1. Concomitant diseases that influence metabolic control (e.g. anemia, significantly impaired hepatic function, renal failure, history of adrenal insufficiency) or other medical conditions, which in the investigator's opinion, may compromise patient safety; Note: Adequately treated thyroid disease and celiac disease do not exclude subjects from enrollment.

2. Significant co-morbidity that, in the opinion of the investigators would preclude participation in the study (e.g. current treatment for cancer, mental disorder)

3. Subject is taking or has taken oral or parenteral glucocorticoids within 1 month prior to screening, or plans to take oral or parenteral glucocorticoids during the study. Exceptions: Short term oral glucocorticoids up to 7 days, inhaled steroids.

4. Subject is taking antidiabetic agents or other medications, which could be a contraindication to participation in the study by the judgment of the investigator.

5. Subject is participating in another study of a medical device or drug that could affect glucose measurements or glucose management or Receipt of any investigational medical product within 1 month prior to screening (Visit 1).

6. Female subject of child-bearing potential who is pregnant, breast-feeding, or planning to become pregnant during the study.

7. Subject has a history of one or more episodes of Diabetic Ketoacidosis (DKA) requiring hospitalization within a month prior to the screening.

8. Subject has current or recent history of alcohol or drug abuse.

9. Subject has visual impairment or hearing loss, which in the investigator's opinion, may compromise patient ability to perform study procedures safely (child and parent should be evaluated as a unit).

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