Objective: To determine the prevalence of diabetes in Southern California emergency department (ED) patients and describe the self-reported general health, demographic and social characteristics of these patients with diabetes. Methods: Between April 2008 and August 2008, non-critical patients at two Southern California EDs completed a 57-question survey about their chronic medical conditions, general health, social and demographic characteristics. Results: 11.3% of the 1,303 patients surveyed had diabetes. Patients with diabetes were similar to ED patients without diabetes with respect to gender, ethnicity and race. However, patients with diabetes were older (51 vs. 41), less likely to have a high school education (64.0% vs. 84.7%), less likely to speak English (44.9% vs. 55.4%), and less likely to be uninsured (33.3% vs. 49.5%). Additionally, patients with diabetes had markedly lower self-reported physical health scores (37.1 vs. 45.8) and mental component score and mental health scores (42.0 vs. 47.4) compared with ED patients without diabetes. Conclusion: In this study of two Southern California EDs, 11.3% of surveyed patients had diabetes. These patients were often poorly educated, possessed limited English language skills and poor physical health. ED personnel and diabetes educators should be mindful of these findings when designing interventions for ED patients with diabetes. [West J Emerg Med. 2010; 11(5):419-422.]