This trial is conducted in Europe. The aim of the trial is to investigate the postprandial glucose metabolism after treatment with faster-acting insulin aspart in subjects with type 1 diabetes.

Inclusion Criteria:

• Male or female aged 18-64 years (both inclusive) at the time of signing informed consent
• Subjects diagnosed (clinically) with type 1 diabetes mellitus at least 365 days prior to the day of screening
• Body mass index 18.5-28.0 kg/m^2 (both inclusive)

Exclusion Criteria:

• Smoker (defined as a subject who is smoking at least five cigarettes or the equivalent per day) who is not able or willing to refrain from smoking or use of nicotine gum or transdermal nicotine patches during the inpatient period
• Subject who has donated any blood or plasma in the past month or more than 500 mL within 3 months prior to screening