This trial is conducted in Asia and Oceania. The aim of this trial is to compare the efficacy and safety of human insulin produced by the current process and the NN729 process in type 1 diabetes.

Inclusion Criteria:

• Duration of diabetes for at least 12 months
• Basal/bolus treatment with human insulin for at least 2 months preceding trial start
• Body Mass Index (BMI) lesser than or equal to 35.0 kg/m2
• HbA1c lesser than or equal to 12.0%

Exclusion Criteria:

• Proliferative retinopathy or maculopathy requiring acute treatment or laser treatment within the last 6 months
• Any condition that the investigator and/or sponsor feel would interfere with trial participation
• Known or suspected allergy against trial product or related products