2. )Type 1 diabetes mellitus (as diagnosed clinically) ≥ 12 months prior to screening visit 3.)Male or female, aged 18 - 64 years (both inclusive) 4.) Body mass index (BMI) 18.0 - 28.0 kg/m2 (both inclusive) 5.) HbA1c 42 - 80 mmol/mol (6.0-9.5%) 6. )Treated with daily insulin injections or continuous s.c. insulin infusion (CSII) ≥ 12 months. Stable insulin dose as judged by the investigator.