Carotid intima media thickness is associated with plasma lipoprotein-associated phospholipase A2 mass in nondiabetic subjects but not in patients with type 2 diabetes

Background A recent meta-analysis showed that both plasma lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) mass and activity independently predict cardiovascular events. Notably, Lp-PLA(2) activity but not mass was found to be a determinant of cardiovascular outcome in type 2 diabetes mellitus. We questioned whether relationships of carotid intima media thickness (IMT), a measure of subclinical atherosclerosis, with Lp-PLA(2) mass differ between diabetic and nondiabetic subjects. Materials and methods Relationships of IMT with plasma Lp-PLA(2) mass (turbidimetric immunoassay) were compared in 74 patients with type 2 diabetes and in 64 nondiabetic subjects. Results IMT was increased (P=0.016), but plasma Lp-PLA(2) mass was decreased in patients with diabetes compared to nondiabetic subjects (277 +/- 66 vs. 327 +/- 62 mu g L-1, P<0.001). In nondiabetic subjects, IMT was correlated positively with Lp-PLA(2) (r = 0 325, P<0.009); multiple linear regression analysis confirmed an independent association of IMT with Lp-PLA(2) (beta = 0.192, P = 0.048). In contrast, IMT was unrelated to Lp-PLA(2) in patients with diabetes (r=0.021, P=0.86), and the relationship of IMT with Lp-PLA(2) was different in diabetic and control subjects (P<0.001). The relationship of Lp-PLA(2) with the total cholesterol /high-density lipoprotein (HDL) cholesterol ratio also differed between diabetic and nondiabetic subjects (P<0 001). Conclusions Plasma Lp-PLA(2) may relate to early stages of atherosclerosis development. In diabetes mellitus, in contrast, the association of IMT with plasma Lp-PLA(2) mass is abolished, which could be partly ascribed to redistribution of Lp-PLA(2) mass from apolipoprotein B-containing lipoproteins towards HDL. These findings raise questions about the usefulness of plasma Lp-PLA(2) mass measurement as a marker of subclinical atherosclerosis in type 2 diabetes mellitus.