To evaluate the prevalence and trend of metabolic syndrome (MetS) among Korean adolescents.

Data from 1998, 2001, and 2005 Korean National Health and Nutrition Examination Surveys were analyzed (N = 4164; age, 10 to 19 years) for MetS prevalence using the modified International Diabetes Federation criteria.

The combined prevalence of MetS in Korean adolescents was 2.2% in 1998, 3.6% in 2001, and 1.8% in 2005. MetS in Korean boys increased from 1.4% in 1998 to 5.3% in 2001 but decreased to 2.0% in 2005. The prevalence of MetS in girls decreased over the study periods (3.0% in 1998, 1.9% in 2001, and 1.6% in 2005). MetS prevalence declined from 1998 to 2005 despite an increase in overweight or obese individuals among both sexes (1998: boys, 15.1%; girls, 17.8%; 2005: boys, 26.8%; girls, 21.7%). Among individual MetS components, hyperglycemia decreased dramatically in 2005 in both sexes and accounted for the majority of the decline in the prevalence of the MetS in Korean adolescents.

The prevalence of MetS has declined despite an increase in obesity in Korean youth. Recent changes in physical activity in addition to national health care initiatives in Korea may have had a positive impact on the prevalence of MetS.