Background: Comorbid depression and diabetes mellitus (DM) compound challenges to disease management such as low health literacy, insufficient access to care, and social or linguistic isolation. Korean Americans (KAs), predominantly first-generation immigrants, suffer from a high prevalence of type 2 DM and depression. Limited research on KAs has prevented the development of effective interventions. Objectives: To compare the prevalence of depression in KAs with DM and all Americans with/without DM, and to explore correlates of comorbid DM and depression and strategies to address KAs’ DM and depression. Methods: KAs’ data were from a clinical trial of a community-based self-help intervention to improve KAs’ DM and mental health outcomes. National Health and Nutrition Examination Survey data sets enabled comparison. Clinical indicators included hemoglobin A1C, lipid panel, and body mass index. Psychobehavioral indicators included self-efficacy for DM management, quality of life, and depression (Patient Health Questionnaire-9 (PHQ-9)). Results: More KAs with DM had depression (44.2%) than did all Americans with DM (28.7%) or without DM (20.1%). Significantly more KAs with DM had mild (29.3%) or clinical (14.9%) depression than did Americans with DM (mild, 17.2%; clinical, 11.5%) or without (mild, 13.8%; clinical, 6.3%). One of six KAs with DM (16.9%) thought of suicide or self-harm (Americans with/without =5.0%, 2.8%). The self-help intervention reduced the mean PHQ-9 from 5.4 at baseline to 4.1 at 12 months. Limitations: External validity might be limited; KAs’ data were from one study site. Conclusions: The prevalence of depression and DM among KAs warrants the development of efficacious interventions.