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±62μgL(-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) (ß=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.
(© 2011 The Authors. European Journal of Clinical Investigation © 2011 Stichting European Society for Clinical Investigation Journal Foundation.)