Students with type 1 diabetes (T1D) need to take responsibility for their T1D and need professional support from school nurses. This study describes school nurses' experiences in supporting students with T1D in school. A qualitative approach was used. After purposive sampling, six school nurses were interviewed and data were analyzed with qualitative content analysis. For professional support, a network around the student was enabled constituting of a continuous dialogue and responsibility and preparedness. For professional support a mutual commitment from the student, parents, and the school nurse was needed which was built from initiating participation and security, the school nurse's ability to be present and available and on school nurse's perceived competence. The conclusion of the study, and its practical implication, is that school nurses' ability for professional support of students with T1D varied in relation to their perceived competence in nursing science as well as their ability to enable, strengthen and sustain teamwork and family-school team meetings.