Background: Metabolic syndrome (MetS) and its components increase the risk of developing cardiovascular diseases, type 2 diabetes, and all-cause mortality. Reports on the trends of MetS and its components in longitudinal studies are scarce, especially in low- and middle-income countries. This study was designed to investigate the prevalence and trends of MetS and its components in a cohort of Iranian adults from 2001 to 2013.

Methods: Participants were followed up for 12 years in a longitudinal population-based study of 6500 adults aged 35 years and older in 2001. Participants were randomly selected from three provinces in central Iran. Sociodemographic characteristics, anthropometry, blood pressure, and various biochemical indices were collected in 2001, 2007, and 2013. Secular trend and age-adjusted trend of MetS and its components were calculated from 2001 to 2013.

Results: The standardized prevalence of MetS, hypertension, low high-density lipoprotein cholesterol (HDL-C), abdominal obesity, and diabetes/impaired glucose tolerance (IGT) increased over the 12 years (6.9%, 5.5%, 12.0%, 2.3%, and 18.7%, respectively), while the prevalence of hypertriglyceridemia decreased by 15.5% during this period. The prevalence of MetS, low HDL-C, and abdominal obesity were higher in females than males in all three phases. Moreover, the increases in the prevalence of these metabolic abnormalities were higher in the rural population than in the urban population.

Conclusions: The present study underscored the increasing trends in MetS and most of its risk factors, thus, to prevent an increase in the cardiovascular risk factors, there is a need to improve lifestyle by education, screening, and treatment of abnormalities.