There has been growing evidence that low grade activation of theimmune system plays a role in the pathogenesis of insulin resistance andtype 2 diabetes mellitus. This study is based on the hypothesis that asingle nucleotide polymorphism in the promoter region of Interleukin-6gene influences its transcription and thus affects plasma level ofInterleukin-6.This will in turn lead to insulin resistance and consequentlytype 2 diabetes.This study was carried out in Kasr Al-Ainy Hospital on 60subjects: 30 known diabetic patients (15 obese and 15 lean) and 30 nondiabeticsubjects (15 obese and 15 lean).In the current study, serum level of Interleukin-6 was assayed byenzyme chemiluminescence and -174 G/C gene polymorphism wasdetected by PCR-RFLP.Serum level of IL-6 was found to be high in the obese group, bothdiabetic and non-diabetic and in the lean diabetic group. As for IL-6genotyping, we found that 58% of the obese carrying the GG genotypedeveloped type 2 diabetes versus 38% of those carrying the C allele.Therefore, this might suggest a protective role for the C allele in thepresence of obesity.