A Study to Look at How Insulin NNC0471-0119 Works in the Body in People With Type 1 Diabetes When Injected by Insulin Pump

This study is looking at the effect and safety of 3 formulations of the new rapid-acting insulin analogue NNC0471-0119, for the treatment of type 1 diabetes when given by insulin pump. The study will test how 3 different formulations of insulin NNC0471-0119 are tolerated by the body, how they are transported in participants bloodstream, how long they stay there and how the blood sugar is lowered. The 3 formulations of insulin NNC0471-0119 are given as one bolus on top of a constant insulin basal rate and compared to Faster Aspart (Fiasp®). Participants will get 3 formulations of insulin NNC0471-0119 and Faster Aspart (Fiasp®) Insulin NNC0471-0119 is a new rapid-acting insulin designed to be used in an insulin pump. Faster Aspart (Fiasp®) is a globally used medication for the treatment of diabetes. Participants will have each study medicine administered once via pump at separate study visits. This mean that participants will have a total of 4 dosing visits where participants will get a study medicine. Which study medicine participants get at what visit will be decided by chance. The study will last 1-4 months. Participants will have 7 visits at the clinic, 4 of them will require an in-house stay of 3 consecutive days each. During the in-house visits 2 intravenous (into the vein) cannulas will be inserted for blood sampling and infusions. Women: Women cannot take part if they are of childbearing potential.