This research study will investigate whether dasiglucagon as a rescue therapy for participants under 6 years of age works and is safe to use. In addition, the study will investigate how dasiglucagon works in the body (pharmacokinetics and pharmacodynamics).

Participants will receive 1 single dose as an injection under the skin (subcutaneous, s.c.) into the buttocks.

Participants will have 3 visits with the study team. For each participant, the study will last up to 84 days.

This trial will use a single-administration, open-label trial design to assess the ability of a single SC injection of dasiglucagon to increase plasma glucose in pediatric children with T1D with hypoglycemia. A total of 8 children will be included; 4 children receiving a dose of 0.3 mg and 4 children receiving a dose of 0.6 mg. Of the 4 children receiving 0.3 mg, 2 children should preferably be below 2 years at screening. The 2 additional children receiving 0.3 mg should weigh below 15 kg at screening and should preferably be below 4 years at screening. For children receiving the 0.6 mg dose, all must be above 2 years at screening. Before an eligible child is dosed, the dose level (0.6 mg or 0.3 mg) must be confirmed by the sponsor. Each child will be dosed after the safety assessment of the preceding child has been completed and assessed by the Trial Safety Group.

The trial will include the following visits:

• A screening visit (Visit 1) in the period from Day - 50 to Day - 29 (pre-treatment visit)
• A dosing visit (Visit 2), Day 1 (day of single dosing with investigational medicinal product [IMP])
• A Safety follow-up visit (Visit 3) at Day 29 +5 days (the end-of-trial visit).

The primary endpoint of the trial is plasma glucose change from baseline at 30 minutes after IMP injection or at the time of rescue by intravenous glucose. Pharmacodynamics (PD) i.e., plasma glucose will be assessed at baseline and 15 and 30 minutes after dosing, while the glucose levels will be monitored by continuous glucose monitoring and by a plasma glucose analyzer during the dosing visit (Visit 2). Pharmacokinetics (PK) will be assessed throughout a 300-minute period at the dosing visit (Visit 2). Safety will be assessed prior to dosing and throughout a 300-minute period after dosing and again at the follow-up visit.

Inclusion Criteria:

• Participants who are confirmed as having T1D based on medical history and are receiving daily insulin therapy via insulin pump or MDI
• Body weight greater than 8 kg
• Child must be <6 years of age at the time of screening
• Further inclusion criteria apply

Exclusion Criteria:

• Known or suspected allergy to the IMP or related products
• Any condition that in the investigators opinion may result in diminished hepatic glycogen stores (e.g., prolonged fasting (more than 24 hours) at Visit 2
• History of anaphylaxis or symptoms of severe systemic allergy (such as angioedema)
• History of hypoglycemic events associated with seizures
• Further exclusion criteria apply

Safety analysis set (SAF) included all participants who were enrolled and received at least 1 dose of investigational medicinal product (IMP).

From first dose of study drug up to end of follow up (up to Day 29)