Inclusion Criteria:  Age = 13-17 years T1D duration ≥ 2 years Insulin pump therapy ≥ 1 year Using CGM or isCGM (Flash Libre) HbA1c ≤ 9.0% (75 mmol/mol) Using carbohydrate counting  Exclusion Criteria:  Allergy to glucagon or lactose Allergy to faster insulin aspart (FiAsp) Pheochromocytoma Self-reported lack of hypoglycemia symptoms when blood glucose is < 3.0 mmol/l Inability to follow study procedures, e.g. exercise, sleeping, blood sampling, and meal intake Pregnancy, nursing, plan to become pregnant or sexually active and not using adequate contraceptive methods (intrauterine device, contraceptive pill, patch or injection) Use of anti-diabetic medicine (other than insulin), corticosteroids or other drugs affecting glucose metabolism during or within 30 days prior to study participation Other concomitant medical or psychological condition that according to the investigator's assessment makes the participant unsuitable for study participation