Objectives: to identify the beliefs of people with Type 2 Diabetes Mellitus related to insulin use.
Methods: a descriptive, cross-sectional, quantitative-qualitative study based on Theory of Planned Behavior and performed with 32 participants using insulin. The data were analyzed and grouped into categories by beliefs similarity, counted from the frequencies.
Results: 118 behavioral, 60 normative and 97 control beliefs were issued. Among the behavioral beliefs, there was an advantage in keeping the diabetes under control and disadvantage, the pain of being pierced by the application of insulin. Regulations highlighted the children as referents who support the treatment. In control beliefs, it was observed that the application of insulin appears as easiness and difficulty to the treatment.Conclusions: the study will support the construction of a psychometric scale to measure the determinants of insulin use, revealing particularities for the structuring of educational interventions that contribute to adherence of the treatment verified in adequate glycemic control.