Inclusion Criteria:  Informed Consent as documented by signature Type 1 Diabetes mellitus as defined by WHO for at least 1 year or is confirmed C-peptide negative (<100pmol/l with concomitant blood glucose >4 mmol/l) Subjects aged between 21-60 years HbA1c ≤ 9.0 % based on analysis from central laboratory Functional insulin treatment with insulin pump therapy or basis-bolus insulin for at least 3 months with good knowledge of insulin self-management Passed driver's examination at least 3 years before study inclusion. Possession of a valid Swiss driver's license. Active driving in the last 6 months before the study.  Exclusion Criteria:  Contraindications to the drug used to induce hypoglycaemia (insulin aspart), known hypersensitivity or allergy to the adhesive patch used to attach the glucose sensor Women who are pregnant or breastfeeding Intention to become pregnant during the study Lack of safe contraception, defined as: Female participants of childbearing potential, not using and not willing to continue using a medically reliable method of contraception for the entire study duration, such as oral, injectable, or implantable contraceptives, or intrauterine contraceptive devices, or who are not using any other method considered sufficiently reliable by the investigator in individual cases. Other clinically significant concomitant disease states as judged by the investigator (e.g., renal failure, hepatic dysfunction, cardiovascular disease, etc.) Known or suspected non-compliance, drug or alcohol abuse Inability to follow the procedures of the study, e.g. due to language problems, psychological disorders, dementia, etc. of the participant Participation in another study with an investigational drug within the 30 days preceding and during the present study Previous enrolment into the current study Enrolment of the investigator, his/her family members, employees and other dependent persons Total daily insulin dose >2 IU/kg/day. Specific concomitant therapy washout requirements prior to and/or during study participation Physical or psychological disease is likely to interfere with the normal conduct of the study and interpretation of the study results as judged by the investigator (especially coronary heart disease or epilepsy). Current treatment with drugs known to interfere with metabolism (e.g. systemic corticosteroids, etc.) or driving performance (e.g. opioids, benzodiazepines) Patients not capable of driving with the driving simulator or patients experiencing motion sickness during the simulator test driving session.