This trial is conducted in Europe. The aim of the trial is to investigate the pharmacokinetic (the exposure of the trial drug in the body) and pharmacodynamic (the effect of the investigated drug on the body) properties of FIAsp (faster-acting insulin aspart) in subjects with type 1 diabetes.

Inclusion Criteria:

• 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 more than 5 cigarettes or the equivalent per day)
• Not able or willing to refrain from smoking and use of nicotine substitute products during the inpatient period inpatient period