Associations of IDL cholesterol and LDL α-tocopherol with diabetic kidney disease in type 2 diabetes

Aims Patients with type 2 diabetes mellitus (T2DM) commonly exhibit atherogenic dyslipidemia and increased oxidative stress, which may contribute to the development and progression of diabetic kidney disease (DKD). We investigated the associations of intermediate-density lipoprotein cholesterol (IDL-C) and α-tocopherol in low-density lipoprotein (LDL-α-tocopherol) with renal dysfunction in T2DM. Methods A total of 188 outpatients with T2DM were categorized into tertiles according to estimated glomerular filtration rate (eGFR). Lipoprotein fractions (HDL-, LDL-, IDL-, and VLDL-cholesterol) and LDL-α-tocopherol content were quantified using anion-exchange high-performance liquid chromatography. Arterial stiffness was assessed by brachial-ankle pulse wave velocity. Multivariable analyses were performed to evaluate associations between eGFR, lipoprotein parameters, and lipid-lowering therapy. Results Declining eGFR was associated with longer diabetes duration and increased arterial stiffness. IDL-C levels and the LDL-α-tocopherol/LDL-C ratio increased significantly across decreasing eGFR tertiles, whereas LDL-C levels showed a decreasing trend. eGFR was independently and inversely correlated with IDL-C and the LDL-α-tocopherol/LDL-C ratio. Statin or fibrate therapy was associated with lower IDL-C levels and higher LDL-α-tocopherol/LDL-C ratios. Conclusions In patients with T2DM, declining DKD is associated with atherogenic IDL accumulation and increased LDL α-tocopherol content, suggesting altered lipoprotein metabolism that may influence LDL oxidation and cardiovascular risk.