Cornelia Huth, Thomas Illig, Christian Herder, Christian Gieger, Harald Grallert, Caren Vollmert, Wolfgang Rathmann, Yasmin Hamid, Oluf Pedersen, Torben Hansen, Barbara Thorand, Christa Meisinger, Angela Doring, Norman Klopp, Henning Gohlke, Wolfgang Lieb, Christian Hengstenberg, Valeriya Lyssenko, Leif Groop, Helen Ireland & 16 others
Background. Several studies have investigated associations between the -174G >C single nucleotide polymorphism (rs1800795) of the IL6 gene and phenotypes related to type 2 diabetes mellitus (T2DM) but presented inconsistent results. Aims. This joint analysis aimed to clarify whether IL6 -174G >C was associated with glucose and circulating interleukin-6 concentrations as well as body mass index (BMI). Methods. Individual-level data from all studies of the IL6-T2DM consortium on Caucasian subjects with available BMI were collected. As study-specific estimates did not show heterogeneity (P>0.1), they were combined by using the inverse-variance fixed-effect model. Results. The main analysis included 9440, 7398, 24,117, or 5659 non-diabetic and manifest T2DM subjects for fasting glucose, 2-hour glucose, BMI, or circulating interleukin-6 levels, respectively. IL6 -174 C-allele carriers had significantly lower fasting glucose (-0.091 mmol/L, P=0.014). There was no evidence for association between IL6 -174G >C and BMI or interleukin-6 levels, except in some subgroups. Conclusions. Our data suggest that C-allele carriers of the IL6 -174G >C polymorphism have lower fasting glucose levels on average, which substantiates previous findings of decreased T2DM risk of these subjects.