Background: According to the Th1/Th2 paradigm, the expansion of Th1-type clones in individuals with type 1 diabetes mellitus results in reduced Th2-type clones, preventing the development of atopic diseases and vice versa. However, there is no consensus regarding the direct or inverse relationship between autoimmune and atopic diseases. Objective: The aim was to examine the knowledge gap about the possibility of coexistence of asthma and T1DM and determine the prevalence of this association. Methods: A scoping review was conducted, following the proposal of the Joanna Briggs Institute. The PCC strategy was used to formulate the guiding question “What is the prevalence of asthma in people with T1DM?”. After excluding duplicate articles, analyzing titles and abstracts, and excluding articles that did not answer the guiding question, 17 articles were included in this review. Results: Most of the articles selected conformed to the Th1/Th2 hypothesis, as the prevalence of asthma was lower in individuals with T1DM. However, similar or higher prevalence of asthma was found between cases and controls in few articles. Conclusion: The prevalence of asthma in people with T1DM ranged from 1.7% to 23.1%. Maybe the mechanisms that characterizes the Th1/Th2 paradigm aren’t as simple as just the interaction of certain cytokines, since Th1-mediated autoimmune diseases and Th2- mediated atopy can coexist.