The purpose of this study is to collect information about Fiasp® to evaluate how effective Fiasp® is in treating elevated blood sugar in patients with type 1 diabetes, compared with the participant's previous insulin treatment. The study will also assess how satisfied the participants are with the treatment with Fiasp® and the impact of the treatment on quality of life. The study has also been set up to learn more about how effective Fiasp® is in controlling the glucose levels during the day and night. The duration of the study is expected to be approximately 2 years. The participation is expected to be approximately 6-8 months for each patient.

Inclusion Criteria:

• Signed consent obtained before any study-related activities (study-related activities are any procedures related to recording of data according to protocol)
• The decision to initiate treatment with commercially available Fiasp® has been made by the patient and the treating physician before and independently from the decision to include the patient in this study
• Male or female, age greater than or equal to 18 years at the time of signing informed consent
• Diagnosed with T1DM at least 1 year prior to inclusion in the study
• Stable treatment by MDI/CSII for at least 6 months prior to inclusion in the study. Stable treatment is defined as not changing the treatment method, with dose adjustments allowed
• Regular (defined as usage on a monthly basis) user of Freestyle Libre® flash glucose monitoring for at least 6 months as the only continuous glucose monitoring (CGM) system actively used and availability of a full 2 weeks sensor download as "csv" file with 80% completeness of the data (if more sensor data are available, the 2 week data closest to baseline visit will be used)
• Latest HbA1c value measured in the 3 months prior to inclusion in the study between 7.5-9.5%

Exclusion Criteria:

• Previous participation in this study. Participation is defined as having given informed consent in this study
• Mental incapacity, unwillingness or language barriers precluding adequate understanding or cooperation
• Anti-diabetic treatment intensification during the last 3 months prior to inclusion in the study. Treatment intensification is defined as adding new anti-diabetic medication to previous treatment regimen
• Female who is pregnant, breast-feeding or intends to become pregnant or is of child-bearing potential and not using adequate contraceptive methods. Only highly effective methods of birth control are accepted (i.e. one that results in less than 1% per year failure rate when used consistently and correctly such as implants, injectables, combined oral contraceptives, certain intrauterine devices), or sexual abstinence or a vasectomised partner

Adult patients with type 1 diabetes mellitus

According to the Novo Nordisk disclosure commitment on novonordisk-trials.com