A Trial Comparing the Effect and Safety of Insulin Degludec Versus Insulin Detemir, Both in Combination With Insulin Aspart, in the Treatment of Pregnant Women With Type 1 Diabetes

The investigators are doing this study to see the effect of insulin degludec in pregnant women with type 1 diabetes, and if it is safe to use. In this study the medicine insulin degludec is compared to another medicine called insulin detemir. Participants will either get insulin degludec or insulin detemir and take it together with a medicine called insulin aspart - which treatment participants get is decided by chance. Participants will get pre-filled insulin pens. Participants will need to take blood sugar measurements several times a day. The study will last between 10 and 25 months depending on whether participants are already pregnant when they join the study. The number of visits and the tests ( for example blood and urine samples and ultrasound scans) the participants will have also depends on whether they are pregnant at study start.