Abstract
Background/Objectives: Diabetes mellitus is defined as a group of metabolic diseases characterized by chronically elevated blood glucose levels. This condition influences the course of orthodontic treatment, as it affects various clinical aspects of the patient that must be taken into consideration prior to initiation. Therefore, achieving adequate control and management of diabetic patients undergoing orthodontic therapy is essential. This article presents a qualitative synthesis of studies addressing how diabetes affects orthodontic treatments, emphasizing the importance of understanding the necessary considerations prior to initiating treatment and how to manage potential complications. Methods: This systematic review was conducted in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. A database search was performed on 5 May 2025, in PubMed, Scopus, Scielo, and The Cochrane Library, using terms related to "diabetes mellitus" and "orthodontic treatments". Studies meeting the search criteria were included, particularly those that were published in the past ten years and reported on the influence of diabetes on orthodontic treatment. The quality of the case-control studies was assessed using the Newcastle-Ottawa Scale (NOS); for cross-sectional studies, the Joanna Briggs Institute (JBI) critical appraisal checklist was used; and for experimental studies, the SYRCLE's Risk of Bias Tool was applied. Results: Fourteen studies ultimately met the inclusion criteria. The evidence showed that diabetes increases gingival bleeding due to elevated levels of advanced glycation end-products (AGEs) and pro-inflammatory cytokines; reduces the efficiency of tooth movement; increases root resorption and affects bone remodeling; and compromises both periodontal and pulpal responses, thereby hindering tissue regeneration. It was also observed that the use of insulin or antidiabetic agents such as metformin may partially mitigate these adverse effects. Conclusions: This systematic review reveals a clear relationship between diabetes and various clinical aspects that influence the progression of orthodontic treatments. Nonetheless, further studies are needed to better understand the impact of this systemic condition on dental treatment outcomes.