Young With Diabetes Type 1 - Test of an mHealth App

Inclusion Criteria: * Type 1 Diabetes * 14 to 22 years old * followed at one of the six diabetes departments/centers 1. Pediatric and Adolescent Department, Nordsjællands Hospital, Hillerød 2. Department of Cardiology, Nephrology and Endocrinology, Nordsjællands Hospital, Hillerød 3. Pediatric and Adolescent Department, Herlev Hospital 4. Steno Diabetes Center, Gentofte 5. Pediatric Department, Roskilde Hospital 6. Department of Endocrinology, Køge Hospital * have an iOS or android smartphone * last measured HbA1c before sending out recruiting letters: 64 mmol/mol or more (if the last measured HbA1c is older than 6 months at time of baseline visit a new HbA1c is measured and has to be at least 64 mmol/mol before the participant kan be randomized) * mean of the three last measured HbA1c before sending out recruiting letters: 58 mmol/mol or more (if the third last HbA1c is older than 18 months at time of baseline visit a new HbA1c is measured and has to be at least 64 mmol/mol before the participant kan be randomized) Exclusion Criteria: * A psychical or psychiatric disorder that enables them to use the app * Participates in other diabetes interventions * Sees a psychologist or psychiatrist * Have participated in developing the app Young with Diabetes