This trial is conducted in Europe. The aim of this trial is to investigate the pharmacodynamic (the effect of the investigated drug on the body) response of Faster acting insulin aspart (FIAsp) in subjects with type 1 diabetes.

Inclusion Criteria:

• Male or female aged 18-64 years (both inclusive) at the time of signing informed consent
• Type 1 diabetes mellitus (as diagnosed clinically) for at least 12 months
• Body mass index 18.5-28.0 kg/m^2 (both inclusive)

Exclusion Criteria:

• Subject who has donated any blood or plasma in the past month or more than 500 mL within 3 months prior to screening
• Smoker (defined as a subject who is smoking at least one cigarette, cigar or pipe daily)
• Not able or willing to refrain from smoking and use of nicotine substitute products during the inpatient period