Objective: To identify the prevalence of and factors associated with diabetes mellitus in rural traditional communities. Methods: Cross-sectional study carried out in 115 rural communities distributed in 45 municipalities in the state of Goiás, including: 13 river communities, 51 quilombolas and 63 agrarian reform settlements. Probabilistic sampling was performed, and participants were selected at random. The outcome variable was self-reported diabetes mellitus, while exposure variables were sociodemographic, lifestyle, health conditions and access to health services. Multiple regression was used to determine the association between study variables. Results: Among the 2,537 participants, the overall prevalence of diabetes was 9.8%, with 13.5% in river dwellers, 10.0% in quilombolas and 9.3% in settlers. Factors associated with diabetes were negative self-perception of health, being a former smoker, high blood pressure, hypercholesterolemia, and living in a river community. Conclusion: The results reinforce the need to strengthen strategies for the prevention and control of diabetes and its complications in rural populations, especially among river dwellers.