This trial was conducted in Europe. The aim of this clinical trial was to evaluate the effect on the blood glucose-lowering effect of NN1250 (insulin degludec) in subjects with type 1 diabetes.

Inclusion Criteria:

• Type 1 diabetes mellitus (as diagnosed clinically) for at least 12 months
• Current total daily insulin treatment lower than 1.2 (I)U/kg/day
• Body mass index 18.0-28.0 kg/m^2

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 gum or transdermal nicotine patches during the inpatient period
• Supine blood pressure at screening (after resting for 5 min) outside the range of 90-140 mmHg for systolic or 50-90 mmHg for diastolic