Inclusion Criteria:  Written Informed Consent Subject is diagnosed with T1D Subject on CSII (except patch pumps) for at least 6 months Subject using any type of insulin approved for mylife™ YpsoPump®: Fiasp®, NovoRapid®, Humalog®, Apidra®, Lispro Sanofi Subject using a CGM system for at least 6 months Age ≥ 18 Subject willing to continue CSII with mylife™ YpsoPump® during the study Subject willing to use the Dexcom G6 CGM system during the study If the subject wants to use the Dexcom Clarity smartphone app instead of a receiver: Subject ensures to use a compatible smartphone and is willing to share CGM for the duration of the study HbA1c < 9.5% (based on last measurement by treating physician)  Exclusion Criteria:  Known allergy/hypersensitivity to medical grade adhesives and/or to physical activity tracker material Known severe nickel allergies History of frequent catheter abscesses associated with pump therapy Treatment with > 1000 mg of acetaminophen every 6 hours Treatment with hydroxyurea Serious acute or chronic disease besides diabetes mellitus or an anamnesis which might, in the opinion of the investigator, pose a risk to the subject, e.g. seizure disorder, adrenal disorder, dialysis for renal failure, cystic fibrosis, active infection Severe late complications of diabetes mellitus, e.g. severe macro- and/or micro-angiopathy (as determined by the investigator) Known hypoglycaemia unawareness Occurrence of self-reported severe hypoglycaemia event requiring third-party assistance within the last 6 months prior to study start Occurrence of self-reported diabetic ketoacidosis requiring healthcare assistance within the last 6 months prior to study start Participation in another investigation with an investigational drug or a pre-market medical device within the 30 days preceding and during the present investigation Female subjects: pregnancy, lactation period, lack of a negative urine pregnancy test (except in case of menopause, sterilization or hysterectomy), or unwilling to use a contraception during the study (for sexually active subjects of childbearing potential) Dependency from the sponsor or the clinical investigator Inability to follow the procedures of the investigation, e.g. due to language problems, psychological disorders, dementia, etc. of the subject