The role of paraoxonase (PON) enzyme in the extent and severity of the coronary artery disease in type-2 diabetic patients

Increased coronary artery disease (CAD) risk is well established in diabetes mellitus (DM). Paraoxonase (PON) enzyme is known to have protective effects on lipid peroxidation. This study aimed to investigate the changes in PON activity levels with duration of DM as well as the role of PON activity in progression of CAD. Eighty-four consecutive diabetic patients (mean age 58 years, 46 men) who underwent coronary angiography for diagnostic purposes were examined. Before the angiography, fasting venous blood samples were taken for PON enzyme activity, thiobarbituric acid reactive substances (TBARS), and routine biochemical parameters. Severity and extent of coronary atherosclerosis were scored numerically using the Gensini scoring system. The population was divided into three groups according to Gensini score: Group 1, mild CAD; Group 2, moderate CAD; Group 3, severe CAD. Group 1 had higher PON levels and shorter DM duration than those of Group 3. Gensini score was significantly correlated with, PON activity (r = −0.361) and apo-AI (r = −0.375). TBARS (r = −0.290) and the duration of DM (r = −0.336) also showed a significant correlation with PON activity levels. Also, multivariate linear regression and Pearson correlation analyses showed that PON activity (P = 0.04), apo-AI levels (P = 0.01), and the duration of DM (P = 0.003) were significantly associated with Gensini score. Paraoxonase activity decreases parallel to DM duration. The lack of protective effect of PON enzyme on lipid peroxidation may be a factor in acceleration of CAD in DM.