Variations in association of Interleukin 6 -G174C single nucleotide polymorphism with type 2 diabetes mellitus—a review

Abstract

Inflammation plays a role in the etiology of type 2 diabetes mellitus (DM). Interleukin-6 is one of the inflammatory markers which play role in the pathogenesis of diabetes mellitus DM. Single nucleotide polymorphism (SNP); -G174C in interleukin −6 (IL-6) gene promoter area has been reported to be associated with type 2 DM (T2DM). The frequency of polymorphism is found to be variable in various ethnic groups and also within an ethnic group. Many studies reported a positive association between T2DM and IL-6 SNP although quite a number of other studies failed to find such association. IL-6 polymorphism has been found to be associated with higher serum IL-6 levels, insulin resistance and BMI, although these findings are also challenged by many studies. There is no single explanation for such highly variable results in different studies. Presence of yet unidentified gene polymorphism in linkage disequilibrium with IL-6 SNP could be responsible. The different results can also be attributed to the study groups differing as age, gender distribution, age of onset of disease, life style, degree of obesity and glucose tolerance. This review highlights the varying results reported in association of IL 6 –G174C SNP with risk of T2DM, serum IL-6 levels, BMI and insulin resistance.