Objective: Given the importance of the association between diabetes and periodontal disease, the main objective of the present study was to compare the microbial diversity responsible for gingivitis in patients with and without type 2 diabetes.Methods: Samples were collected from the oral cavity of 134 patients with gingivitis and categorised into 3 groups (68 non-diabetic patients and 66 diabetic patients; 33 with controlled diabetes and 33 with poorly controlled diabetes). Sample culture was carried out on selective culture media. The identification of isolated strains involved a series of biochemical tests including miniature galleries (API 20E and 20 Strep), the traditional biochemical gallery (tubes) and automated bacterial identification (BD Phoenix™).Results: Identification by biochemical methods made it possible to differentiate 14 bacterial species and one yeast. There was greater bacterial diversity in diabetic patients as compared to non-diabetic patients. Periodontal pathogens were isolated from both diabetic and non-diabetic populations; however, certain microbes such as Streptococcus acidominimus, Enterobacter cloacae, Klebsiella oxytoca, and Pseudomonas aeruginosa were present only in diabetics, with a much higher percentage in those with poorly controlled diabetes.Conclusion: Poorly controlled diabetes causes metabolic dysregulation that can increase the severity of periodontal disease.