Association of low-grade inflammation with nephropathy in type 2 diabetic patients: Role of elevated CRP-levels and 2 different gene-polymorphisms of proinflammatory cytokines

Background: Chronic inflammatory processes are thought to play a key role in the development of micro- and macrovascular complications in type 2 diabetes mellitus. An association between low-grade inflammation and type 2 diabetes has been described in some studies. We assayed the association of two frequent polymorphisms in proinflammatory cytokines: the interleukin 6 G(-174)C promoter polymorphism [IL-6G(-174)C], the exon 2 interleukin receptor antagonist insertion deletion polymorphism [IL1RA]) and serum CRP levels with the prevalence of diabetic nephropathy in patients suffering from type 2 diabetes mellitus. Subjects and methods: A total of 141 patients with type 2 diabetes mellitus, with and without diabetic nephropathy was genotyped for the above mentioned polymorphisms: 66 with normoalbuminuria, 31 with microalbuminuria and 44 with macroalbuminuria. CRP levels were analysed by a high sensitivity - immunnephelometric assay. Results: While a significant association between macroalbuminuria and CRP could be observed (p < 0,0 15), no associations were found between IL-6G(-174)C or IL1RA genotype and any stage of nephropathy. CRP-levels were similiar in the 3 different IL-6G(- 1 74)C genotypes as well as in the 2 IL1RA genotypes. Conclusions: in type 2 diabetic subjects elevated CRP levels are associated with an increased prevalence of albuminuria. The two investigated proinflammatory polymorphisms do not seem to contribute to initiation of nephropathy in type 2 diabetic patients but we cannot exclude effects of these polymorphisms on course of nephropathy.