Patient description: A 16-year-old girl came to the clinic complaining of weight gain and abnormal menstrual cycles. Her BMI was 24, but she has gained 5 kg in the past few weeks. She gets tired more frequently and does not have energy to go dancing with her friends. Her lab results were remarkable for high TSH levels (15 mU/L) and low free T4 levels (0.18 ng/dl). Her anti-TPO levels were extremely high (136 IU/ml). She was diagnosed with Hashimoto disease. She does not smoke and she is not sexually active.

Clinical trial eligibility criteria: eligible ages (years): 10.0-17.0,  Type 1 Diabetes Mellitus Informed consent signed by a parent/legal guardian and informed assent signed by the study participant prior study entry Diagnosed with T1D, as defined by the American Diabetes Association and World Health Organization (ADA/WHO) for at least 1 year prior to study enrolment Documented evidence should exist within the patient history of T1D Age between 10 and 17 years (inclusive) at the time of enrolment Treatment with insulin pump therapy for at least 3 months HbA1C value ≤ 9% based on analysis from the local laboratory at the time of enrolment (A1C testing must follow National Glycohemoglobin Standardization Program (NGSP) standards) Willing to follow all study instructions (child and parent should be evaluated as one) Availability for the entire study duration and follow-up visits Willing to perform daily self-monitoring of blood glucose (SMBG) and required sensor calibrations If also present celiac/Hashimoto disease, the disease has to be adequately treated as determined by the investigator  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 subjects from enrollment Significant co-morbidity that, in the opinion of the investigators would preclude participation in the study (e.g. current treatment for cancer, mental disorder) Any concomitant oral or parenteral glucocorticoids therapy within 1 month prior to screening, or planning to take oral or parenteral glucocorticoids during the study. (Exceptions: Short term oral glucocorticoids up to 7 days, inhaled steroids) Any concomitant therapy with antidiabetic agents or other medications, which could be a contraindication to participation in the study by the judgment of the investigator Participation 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) Female subject of child-bearing potential who is pregnant, breast-feeding, or planning to become pregnant during the study Subject that has known hypoglycemic unawareness or recurrent severe hypoglycemic events with seizure and/or coma (more than two episodes) within 6 months prior to screening History of one or more episodes of Diabetic Ketoacidosis (DKA) requiring hospitalization within a month prior to the screening Current or recent history of alcohol or drug abuse 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)