Object: We aimed to estimate the prevalence of metabolic syndrome in patients with type 1 diabetes mellitus compared to the age- and sex-matched patients with type 2 diabetes mellitus. Methods: Clinical characteristics and prevalence of metabolic syndrome in individuals with type 1 diabetes mellitus between 2009 and 2013 were determined using the database of Korean National Health Insurance Service (NHIS) preventive health checkups. Results: Age- and sex-adjusted prevalence of metabolic syndrome in patients with type 1 diabetes was 51.65-55.06% between 2009 and 2013. Among the individual components of metabolic syndrome, the prevalence of hypertriglyceridemia differed the most between patients with prevalent type 1 and type 2 diabetes. The prevalence of high BP in individuals with type 1 diabetes was comparable to that in age- and sex-matched patients with type 2 diabetes mellitus. Conclusion: Metabolic syndrome may be a frequent finding in individuals with type 1 diabetes in Korea.