The association of the 174G > C polymorphism of interleukin 6 gene with diabetic nephropathy in patients with type 2 diabetes mellitus

AimsTo evaluate the association of 174G > C polymorphism on interleukin-6 (IL-6) gene with diabetic nephropathy in patients with type 2 diabetes.MethodsA total of 393 Greek subjects with type 2 diabetes (mean age 66.5 ± 10.0 years, men n = 203, women n = 190) were examined. Diabetic nephropathy was defined as presence of microalbuminuria and/or proteinuria. The IL-6 174G > C polymorphism was detected by polymerase chain reaction and appropriate restriction enzyme digestion. High sensitivity C-reactive protein was assayed by particle-enhanced immunonephelometry.ResultsThe genotype distribution (%) was GG: 49.1, GC: 26.8 and CC: 24.1, with no gender difference. The CC homozygotes had lower albumin excretion (mg/24 h) in comparison with the GC genotype CC: 8.9 (4.0–20.9) vs GC: 21.95 (9.1–53.35), P = 0.004]. Participants with the GC genotype tended to have more frequently nephropathy than those with the GG or the CC genotype GC: 44.55% vs GG: 35.1% and CC: 28.3%, P = 0.07)]. The CC homozygotes in comparison with GC heterozygotes had lower odds to have nephropathy (odds ratio: 0.51, 95% confidence intervals = 0.28–0.91, P = 0.02), even after adjustment for sex, age, duration of diabetes, body mass index, smoking, hypertension, lipids and glycated hemoglobin, (P = 0.01).ConclusionIn type 2 diabetes states, CC homozygotes have lower albumin excretion and are protected from nephropathy in comparison with GC genotypes.