This is a cross-sectional clinical study performed with type 2 diabetes mellitus patients and nondiabetic patients, in the city of Passo Fundo, RS, Brazil, which aimed to verify whether periodontal disease is more prevalent in type 2 diabetes mellitus (DM2) patients. The study sample included 275 patients, wherein 117 were type 2 diabetes patients and 158 were non-diabetic patients, who were assessed between the years of 2007 and 2010. The inclusion criteria of the study were patients older than 35 years with DM2 diagnosed for more than one year through glycemia and glycosylated hemoglobin tests. The same criteria was used for the control group, except for the presence of diabetes. The participants were evaluated by students calibrated for the Periodontal Screening and Recording (PSR) index and through a questionnaire assessing age, gender, oral hygiene conditions, and medications of the patients. Generalized gingivitis was more prevalent in diabetic patients (p<0.001). The level of oral hygiene of the diabetic patients was considered fair and poor (p<0.001) when compared to the non-diabetic patients. More sextants with periodontal health were observed in non-diabetic patients (p<00.1) when compared to type 2 diabetes mellitus patients; tooth loss was also greater in DM2 patients. The study allowed concluding that DM2 patients presented higher prevalence of periodontal disease than the control group. The factors that might have influenced these results were systemic condition (DM2), level of oral hygiene, and age, which justifies the high rate of periodontal disease and tooth loss in these individuals.