Background Brazil ranks fifth in the world in the number of adults with diabetes, and third for type 1 diabetes. Conducting educational actions on this topic in public schools in this country is extremely important, since it can assist in the early adoption of good life habits and in a better care for students in this condition.Objective The aim of this study was to assess the effectiveness of an educational intervention about diabetes for students and school staff. Methods This is an interventional non-randomized longitudinal study, in which interviews were conducted before and after a playful intervention with the use of theater play and games for students and plus a training for the school staff. Results A total of 89 participants completed the study, being 73 students aged 7 to 12 years old, and 16 school staff. As a result, there was a positive change in knowledge and perception of diabetes by the students. The greatest changes in the answers among the participants, at the post-intervention period, were related to the possibility of consuming something with sugar by those with diabetes, and particularly how to cope in hypoglycemia situations by the school staff. Conclusions Actions like these must be encouraged within the school environment, especially in countries with high prevalence of diabetes.