BackgroundThe aim of the present study was to determine the prevalence of metabolic syndrome and its individual components among the Iranian adult population in 2011 and to investigate changes between 2007 and 2011. MethodsData from two rounds of the Surveillance of Risk Factors of Non-communicable Diseases national surveys conducted in 2007 and 2011 were pooled. Metabolic syndrome was defined according to International Diabetes Federation criteria. ResultsIn 2007, the prevalence of metabolic syndrome among adults aged 25-64 years was 35.95 (95% confidence interval [CI] 34.27-37.63), which decreased to 32.96 (95% CI 30.73-35.18) in 2011 (P = 0.0108). Despite this overall decline, the prevalence of central obesity (P = 0.1383), raised triglycerides (P = 0.3058), and reduced high-density lipoprotein cholesterol (HDL-C; P = 0.5595) remained constant. There was a trend towards a decline in the proportion of individuals with increased blood pressure (P = 0.0978), and the proportion of adults with increased fasting plasma glucose (FPG) increased (P < 0.0001). In 2011, the prevalence of central obesity, raised triglycerides, reduced HDL-C, increased blood pressure and increased FPG was 51.88 (95% CI 48.97-54.79), 36.99 (95% CI 34.52-39.45), 54.72 (95% CI 50.87-58.57), 38.92 (95% CI 36.19-41.64), and 24.97 (95% CI 22.02-27.93) respectively. ConclusionsOver the period 2007-11, the prevalence of metabolic syndrome has decreased slightly in Iran, although prevalence of increased FPG has increased significantly. One-third of the Iranian adult population is diagnosed with metabolic syndrome.