PON1 and type 2 diabetes mellitus: In this study, we analyzed the anti-oxidant activity of HDL, as represented by the arylesterase activity of paraoxonase 1 (PON1) in HDL particles, in 216 consecutive HF patients with (n = 79) or without (n = 137) type 2 diabetes, and age- and gender-matched 112 diabetic and 189 non-diabetic non-HF controls.