Deterioration in the health care delivery system has been a growing problem in Korea. The concentration of mild patients with chronic disease in tertiary care centers or general hospitals other than in clinics results in the distortion of functional differentiation among various types of providers. This brings about not a coordination of care through well-organized a referral system but an undesirable competition between clinics and hospitals. In this study, we used a multivariate binary logistic model to estimate the factors associated with the diabetes outpatients' choice of tertiary care centers (TCCs) or general hospitals as their usual source of care. Data were collected from the 2008 Korean Health Panel. The unit of analysis was a diabetes outpatient (n=910). Our study results showed that 56% of all of the diabetes outpatients studied only used clinics for their care during the year of 2008 followed by general hospitals (16%), mixed (12%), TCCs (10%) and hospitals (6%). Among the various types of providers, TCC or general hospital users had the highest out-of-pocket payments per visit, but the lowest number of visits, tests, and prescriptions during the year of 2008. According to our regression analysis, patients with higher education, income, and Charlson Comorbidity Index levels were more likely to use TCCs or general hospitals. Compared with patients who enrolled in the National Health Insurance program, Medical Aid program enrollees were more likely to visit TCCs or general hospitals. In addition, being enrolled in private health insurance or having any disability was also positively associated with the greater use of TCCs or general hospitals. Our findings suggest that policy-makers should take into consideration the characteristics of patients in implementing policies related to the healthcare delivery system. It is also necessary to employ diverse approaches, such as regulation and incentives considering patent characteristics to reform the current defective aspects of health care utilization and provision.