The aims of this study are to evaluate whether diabetic teenagers participating in a group educational programme, ‘the schooner programme’, differ from non-participants in attitudes towards diabetes and self-care, and to evaluate the impact on the attitudes, HbA1c and treatment of the programme. Ninety teenagers aged 14–18 years attended the programme. Attitudes towards diabetes and self-care were measured with a validated questionnaire. Medical data were collected from the medical records. The participants reported more positive attitudes towards diabetes and self-care and more frequent contacts with others with diabetes monitored blood glucose more often and felt less disturbed by diabetes than non-participants. The programme had positive impact on attitudes towards diabetes. There was no change in HbA1c, but the use of insulin pumps was more frequent among participants after the programme. To get teenagers attracted to group education, the diabetes care team needs to influence them towards more positive attitudes.