Background: There is a sound pathophysiological framework for addressing oral health issues in general healthcare given the prevalence of oral diseases and their link to diabetes. However, many individuals with diabetes are unaware of the link between their disease and their oral condition, as well as the fact that they have a higher chance of experiencing a variety of difficulties with their oral health. The goal of this research was to assess the knowledge about oral complications due to diabetes mellitus among diabetes patients in Chengalpattu district, India. Methods: A cross-sectional study including 470 diabetes patients was carried out over a period of 4 months from February to May 2022. Descriptive statistics and multivariate logistic regression analyses were performed using the Statistical Package for the Social Sciences (SPSS) version 21. P<0.05 was considered statistically significant. Results: Many of the study subjects were not aware of the relationship between oral problems and diabetes. The knowledge about oral complications of diabetes was limited to awareness about dental caries (28.9%), periodontal disease (35.1%), xerostomia (51.8%), oral candidiasis (15.7%), and oral cancer (9.6%). Education and the duration of time after a diabetes diagnosis were the two most crucial predictors of awareness of the complications. Conclusion: Regarding the oral problems of diabetes, there is a dearth of knowledge, and this agreement is primarily associated with education and the duration of time from diabetes diagnosis.