2.2.3. Treatment Adherence

To measure patients' treatment adherence in the context of type 1 diabetes management, a 6-item questionnaire was constructed by the authors. More specifically, five aspects of treatment adherence were assessed: (1) following diet, (2) measuring blood sugar, (3) taking insulin shots, (4) keeping glucose diary updated, and (5) appearing regularly to appointments. In addition, the sixth question assessed the overall treatment adherence of patients. The questions were rated on a 3-point Likert scale by the patients' pediatric endocrinologist: 0 = ^“yes,^”1 = ^“sometimes,^” and 2 = ^“no.^” The sixth question could be answered by 0 = ^“good,^”1 = ^“medium,^” and 2 = ^“poor.^” Because this instrument was newly constructed, the structure of the treatment adherence questionnaire was determined with an exploratory factor analysis. Both the Bartlett test (χ²(15) = 634.93, p < .001) and the Kaiser-Meyer-Olkin Measure of Sampling Adequacy (KMO = .83) indicated eligibility for factor analysis. A principal component analysis was calculated with varimax rotation. One factor with eigenvalue >1 was identified. Thus, the factor analyses indicated all six items loading on the same factor. Internal consistency was acceptable (α = .77).