Thrombin activatable fibrinolysis inhibitor (TAFI) is an important procoagulant factor. Patients with metabolic syndrome (MetS) also have an elevated procoagulant status. However, TAFI and its association with MetS are still not well known. We aimed to investigate TAFI in type 2 diabetes mellitus patients with MetS. We enrolled a total of 55 patients who had MetS (n=30) and 25 healthy controls. MetS was diagnosed using National Cholesterol Education Program Adult Treatment Panel III criteria. We measured activated and inactivated TAFI (TAFIa/ai) antigen in plasma samples using a commercially available ELISA kit (Imubind TAFIa/ai antigen ELISA; American Diagnostica Inc., Stamford, Connecticut, USA). TAFIa/ai levels were then evaluated for links to MetS parameters. Mean TAFIa/ai levels were 156.6 +/- 66.9ng/dl in patients with MetS and 104.1 +/- 60.3ng/dl in the control group (P=0.005). None of the MetS parameters, including blood pressure, fasting plasma glucose, waist circumference, triglycerides or high-density lipoprotein cholesterol (HDL-C) levels were correlated with TAFIa/ai levels. However, TAFIa/ai level had a strong correlation with the number of metabolic risk components, which increased proportionally when MetS parameters were over three. When there were increased numbers of MetS risk components, we detected a rise in TAFIa/ai levels. TAFIa/ai levels could be an indicator of atherosclerotic tendency in patients with MetS. (C) 2013 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.