['To explore the hypothesis that a relationship exists between free radical activity and abnormalities in hemostasis in NIDDM.', 'The use of the total radical-trapping antioxidant parameter (TRAP) has very recently been proposed to explore the antioxidant property of a plasma and their mutual cooperation. In the present study, TRAP, vitamin E, vitamin C, vitamin A, uric acid, protein-bound SH (thiol) groups, fibrinogen, prothrombin fragments F1 + 2, and D-dimer have been evaluated in 46 NIDDM patients and 47 healthy matched control subjects.', 'In NIDDM patients, TRAP, vitamin A, SH groups, and uric acid were significantly reduced, whereas the level of vitamin E was significantly increased. Vitamin C was similar in the two groups. Fibrinogen, prothrombin fragment 1 + 2, and D-dimer were increased in diabetic patients. TRAP, but no single other antioxidant, had a strong inverse association with fibrinogen, prothrombin fragment 1 + 2, and D-dimer.'] Does total plasma antioxidant capacity predict thrombosis-prone status in NIDDM patients?