The aim of the study was to assess the prevalence of self-reported diabetes in the elderly, identifying associated factors, knowledge, and practices related to treatment options. This was a cross-sectional population-based study with stratified clustered two-stage sampling in six municipalities in the State of São Paulo, Brazil. Among the 1,949 elderly, 15.4% presented self-reported diabetes. Body mass index and exercising were statistically associated with diabetes. There was a significant difference between diabetics and non-diabetics in terms of self-rated health, hospitalization, self-reported illness in the previous two weeks, and report of the following diseases: hypertension, anemia, chronic kidney disease, and heart disease. In terms of per capita family income, there was no difference in regular medical visits, participation in discussion groups, and control practices. The findings show the need for behavior changes to prevent and control diabetes and its complications. Educational interventions are needed to expand the coverage of diabetes care.