There is a lack of studies demonstrating positive effects on glycaemic control and HRQoL in children and adolescents starting CSII treatment. Guidelines recommend measuring perceived HRQoL routinely. It is important to have questionnaires, not overly comprehensive or timeconsuming, to measure HRQoL in children and adolescents as well as their parents. Structured and person-centred education has been emphasized as a key to successful selfmanagement. Guided Self-Determination-Young (GSD-Y) is a person-centred communication and reflection method. The overall aim of this thesis was to increase the knowledge regarding glycaemic control, type of treatment, HRQoL, and a theory-based education among youth with type 1 diabetes.

Study I was a retrospective case-control study comparing children and adolescents starting CSII (n=216), with a control group treated with MDI (n=215). Children and adolescents who had started CSII showed improvement in glycaemic control, measured as HbA1c, during the first six months. For boys, this improvement could be identified throughout the first year.

In Study II, 197 parents and their children with type 1 diabetes completed the proxy and child versions of the questionnaires Check your Health and DISABKIDS to test the psychometric properties of Check your Health by proxy. The test of the reliability and validity of this questionnaire showed acceptable psychometric properties.

Study III, an RCT evaluating a GSD-Y education, included 71 adolescents starting CSII and their parents. The intervention group (n=37) attended seven group education sessions, lasting for about two hours each, using the GSD-Y method. The participants were followed for six months. The GSD-Y method showed a positive effect on glycaemic control, especially for participants with an HbA1c above 63 mmol/mol (n=48) at inclusion (p= 0.037); furthermore, readiness to change increased (p=0.037). A correlation was identified between HbA1c and goal achievement (rs=-0.475, p=0.001), and readiness to change (rs=-0.487, p=0.001).

In Study IV, 13 adolescents were interviewed after the intervention with GSD-Y. From the qualitative analysis, two categories emerged: the importance of context, and growing in power through the group process. An overarching theme that emerged from the interviews was the importance of expert and referent power in growing awareness of the importance of self-management, as well as mitigating the loneliness of diabetes. Further, the findings showed that it is valuable for adolescents to meet other young people in the same situation, and to share their experiences from living with diabetes.

In conclusion the four studies showed, treatment with CSII may initially result in improved HbA1c. Group education with the GSD-Y method, for adolescents and their parents, has the potential to further improve HbA1c, mitigate the loneliness of diabetes, and contribute to conscious reflection about self-management. The Check your Health questionnaire by proxy has shown acceptable psychometric characteristics, and may be useful in both studies and clinical settings.