Inclusion Criteria:  Signed consent obtained before any study-related activities (study-related activities are any procedure related to recording of data according to the protocol). Male or female, age above or equal to 18 years at the time of signing consent. Diagnosed with T1DM (Type 1 Diabetes Mellitus) for above or equal to 1 year (365 days) at the time of signing consent. On treatment with Tresiba® for more than or equal to 1 month (30 days) and Fiasp® for for more than or equal to 3 months (90 days) at the time of signing consent. The decision to initiate the use of commercially available NovoPen® 6 as a part of treatment with Tresiba® and Fiasp® has been made by the patient/Legally Acceptable Representative (LAR) and the treating physician before and independently from the decision to include the patient in this study. Current user of a rtCGM (Real-Time Continuous Glucose Monitoring) or isCGM (Intermittent-scanning Continuous Glucose Monitoring) for greather than or equal to 2 months (60 days) of which the last 14 days must be on rtCGM or isCGM, which can integrate the data with diabetes treatment support solution from either Glooko or Abbott, at the time of signing consent. Willingness to continue using a rtCGM or isCGM for the duration of the study, which can integrate the data with diabetes treatment support solution from either Glooko or Abbott. Current user of a diabetes treatment support solution from either Glooko or Abbott, which can integrate the NovoPen® 6 injection data and the rtCGM/isCGM data, and willingness to continue using the same solution for the duration of the study.  Exclusion Criteria:  Previous participation in this study. Participation is defined as having given consent in this study. Treatment with any investigational drug within 30 days prior to enrolment into the study. Mental incapacity, unwillingness or language barriers precluding adequate understanding or cooperation. Use of any smart pen or smart cap for the diabetes treatment prior to the signing consent.