Diabetes mellitus is a chronic disease that is increasing at an alarming rate all over the world. The aim of this study was to assess the quality information available on YouTube on diabetes and oral healthcare. This cross-sectional study made a search in YouTube ( https://www.youtube.com/ ). Two reviewers assessed the videos and categorized them into useful, misleading or personal experience, and scored them using a global quality scale (GQS) from 1 to 5 according to their overall quality (1 = poor quality; 5 = excellent quality). The source of each video was also registered, as was user interaction with each video. A total of 97 videos were included for analysis. Of these, 30 (30.9%) contained useful information, 61 (62.9%) contained misleading information, and six (6.2%) recounted personal experiences. Overall quality scores showed statistically significant differences between those containing useful information and those with misleading information and personal experience (p = 0.001). Significant differences in content were also found regarding oral hygiene (p = 0.022), periodontitis (p = 0.002), and infection (p = 0.04). YouTube provides informative videos about oral healthcare for diabetics. The quality of the videos was variable and the videos recorded by dental professionals and Universities showed a higher quality. Further research is needed into oral healthcare for diabetics.