A Study to Test How Insulin NNC0471-0119 H Works in the Body in Participants With Type 1 Diabetes When Given by an Insulin Pump

The study is looking at the effect and safety of a new fast-acting insulin (NNC0471 0119) to people with type 1 diabetes when given by an insulin pump. The study tests how fast insulin NNC0471-0119 enters your bloodstream, how long it stays there and how much it lowers blood sugar. The new insulin NNC0471-0119 will be compared to insulin aspart. The participants will get each study medicine administered at separate clinic visits. The study will last for about 1-3 months.

Inclusion Criteria: * Male or female aged 18-64 years (both inclusive) at the time of signing the informed consent. * Diagnosed with Type 1 Diabetes (T1D) greater than or equal to (≥) 1 year before screening. * Insulin administration using continuous subcutaneous insulin infusion via a pump greater than or equal to (≥) 90 days before screening. * Current daily insulin treatment between 0.2 and 1.2 Insulin units per kilogram per day \[(I)U/kg/day\] (both inclusive). Exclusion Criteria: * Known or suspected hypersensitivity to study intervention(s) or related products. * Female who is pregnant, breast-feeding or intends to become pregnant or is of child-bearing potential and not using adequate contraceptive methods.