Diabetes mellitus is a public health problem due to its incidence and prevalence. As it is a progressive disease, affected people tend to deteriorate their health over time, leading to complications. Although its negative impact on quality of life is recognized, there is a need to analyze it focusing on the context of southeastern Brazil. To fill this gap, this study Aims to evaluate the quality of life in patients with type 2 diabetes mellitus in a city in southeastern Brazil. Through an analytical cross-sectional observational study, we collected data from patients of the university in a city in southeastern Brazil. We applied a survey including questions related to the sociodemographic and clinical information, and from the SF-36 quality of life questionnaire. Descriptive analyzes and the t-test. The final sample consisted of data from 300 patients, mostly female (79.0%), aged over 54 years (73.3%), married or in a stable relationship, and predominantly with lower income and lower education levels. Most patients were obese (48.3%) and did not practice physical activity (67.7%). Regarding the SF-36 domains, the highest average value found was for the Social Aspects domain (73.4). Between males and females, a significant difference was only observed between the scores of the Functional Capacity and Pain domains. Comparing age groupings, individuals with or without obesity, and with or without other comorbidities, significant differences were found for most domains (including Pain and General Health Status). The education level was also significant, with the highest averages in the SF-36 domains being obtained for individuals who had at least completed high school. Physical activity practice was significant for all domains. Evaluating the factors associated with the quality of life of Brazilians, considering the diabetes effects, can contribute to health promotion and disease prevention actions.