OBJECTIVES: To determine the incidence rate of and risk factors for type 2 diabetes-related hospitalization (HOSP) in South Korea. METHODS: We utilized retrospective longitudinal cohort data, obtained from three Catholic University Hospitals in Seoul Korea during 2000-2006.  We selected type 2 diabetes patients who visited the study hospitals between 2002-2004 and followed them until the date of the first diabetes-related hospitalization or the end of the study period. The HOSP was defined as admitted patients with any symptoms, diseases and complications related to diabetes. We determined the risk factors which were observed during the year prior to the hospitalization or the end of the follow-up.  Relative risk (RR) and 95% Confidence Interval (95% CI) were obtained by Cox-proportional hazard models after adjusting for patient demographics and comorbidities.  We also calculated the incidence rate of hospitalization per 100,000 person-year to account for patients’ different follow-up periods. RESULTS: A total of 10,037 eligible diabetic patients were identified with a mean age of 61.6 years old and 53% of them men. Of the total, 926 (9.23%) had HOSP. The overall incidence rate of HOSP was 5,954 per 100,000 person-year.  The rate of HOSP was higher than mean in the elderly (6,963), women (7,119), and patients with chronic renal failure (17,796).The risks of HOSP were significantly increased if diabetic patients were older than 65 years (RR=1.35; 95% CI=1.18-1.54) or women (RR=1.36; 95% CI=1.19-1.55).  Patients were also more likely to be hospitalized if they had comorbid conditions such as chronic renal failure (RR=1.98; 95% CI=1.30-3.02), depression (RR=1.78; 95% CI=1.19-2.65), or dyslipidemia (RR=1.53; 95% CI=1.08-2.18).  Diabetic patients who visited outpatient departments more than 3 times a year reduced a risk of hospitalization by about 80%. CONCLUSIONS: The study findings imply that aggressive treatment aimed at nephroprotective, depression, or dyslipidemia as well as improvement of patients’ adherence to diabetic treatment reduce risks of hospitalizations.