Apolipoprotein E Polymorphism and Renal Function in German Type 1 and Type 2 Diabetic Patients

Abstract

OBJECTIVE To examine the association of renal function in diabetic patients with apolipoprotein (apo) E polymorphism. RESEARCH DESIGN AND METHODS Apo E genotypes, lipid and lipoprotein serum levels, creatinine clearance (CCr), and excretion of marker proteins were determined in German type 1 (IDDM; n = 162) and type 2 (NIDDM; n = 124) diabetic patients. Albumin and immunoglobulin (Ig) G are considered to reflect charge-size permselectivity of the glomerular capillary basement membrane, and increased alpha 1-microglobulin (MG) excretion indicates compromised reabsorptive capacity of the renal tubules. RESULTS Patients with NIDDM had higher lipid levels and lower CCrs than patients with IDDM. In patients with IDDM, age- and sex-adjusted analysis of variance showed an association between apo E genotypes and CCr, and the Jonckheere-Terpstra test demonstrated a decreasing glomerular filtration rate in the following order of genotypes: ε4ε4/ε4ε3 > ε3ε3 > ε2ε2/ε2ε3. Multiple linear regression analyses revealed that in patients with IDDM, the ε2 allele was a negative predictor of CCr and a positive predictor of urinary excretion of albumin, IgG and α 1-MG independent from HDL and LDL cholesterol, TG concentration, age, and sex. CONCLUSIONS Apo E polymorphism influences serum lipoprotein levels in patients with IDDM and NIDDM. Apo E polymorphism may be a renal risk factor of clinical relevance in normolipidemic patients with IDDM.