Association between plasma oxidized low-density lipoprotein and diabetic nephropathy

To investigate the association of oxidized low-density lipoprotein (ox-LDL) with the development of diabetic nephropathy, plasma levels of ox-LDL were measured in 70 patients with type 2 diabetes mellitus. A sandwich enzyme-linked immunoadsorbent assay (ELISA) using the mouse monoclonal antibody FOH1a/DLH3, which specifically recognizes oxidized phosphatidylcholine, and a horseradish peroxidase (HRP)-labeled goat anti-human apolipoprotein B IgG was used to measure ox-LDL levels. The mean age of the patients was 57.0+/-1 3.4 years, and the mean duration of diabetes was 13.4+/-8.5 years. Plasma ox-LDL levels were similar in patients with normoalbuminuria (13.7+/-3.9 U/ml), patients with microalbuminuria (12.8+/-3.9 U/ml), and normal controls (12.5+/-4.2 U/ml). However, the plasma ox-LDL level in patients with macroalbuminuria (16.8+/-7.5 U/ml) was significantly higher than those in the other groups (P<0.05). Hemoglobin A1c (HbA1c) levels were similar in diabetic patients with normoalbuminuria (8.2+/-2.2%), microalbuminuria (7.8+/-1.3%), or macroalbuminuria (7.2+/-1.4%). There was no significant correlation between the ox-LDL level and the HbA1c level. The significantly elevated plasma ox-LDL levels in patients with macroalbuminuria suggest that ox-LDL may play an important role in the progression of diabetic nephropathy.