Chronic diseases pose a major challenge to population health worldwide. Diabetes is a major chronic disease that is managed overwhelmingly in primary care. There is an increasing recognition of the role that primary care physicians play to achieve high-quality care for patients with diabetes. By analyzing 2013 Korean Health Panel data, the authors aimed to determine the current status of having a regular doctor (RD) for adults (aged 18 years or older) with diabetes. In addition, the association of having a RD with the experience of emergency department (ED) visits was determined in this study. Among adults with diabetes, those with RD accounted for 41.0%. The older the age group and the higher the Charlson comorbidity index score, the higher the percentage of adults with diabetes had RD. Even for those with RD, coordination of care was very poor (positive answer: 27.1%). After adjustment for confounding variables, those having (vs. not having) a RD (odds ratio [OR], 0.57; 95% confidence interval [CI], 0.35-0.94), especially those whose RDs delivered good comprehensiveness of care (OR, 0.47; 95% CI, 0.26-0.84) or worked at a primary care clinic (OR, 0.43; 95% CI, 0.22-0.81), and those whose longitudinal relationship with a RD was 5 years or less (OR, 0.45; 95% CI, 0.22-0.91) were less likely to have ED visits within the last year. In conclusion, health care policies that promote having a RD who delivers high-quality primary care could decrease unnecessary ED visits by diabetic adults. This can partly reduce ED overcrowding in Korea.