Association between sex hormone binding globulin gene polymorphism and type 2 diabetes mellitus

This study aims to investigate the relationship between single nucleotide polymorphisms (SNPs) of sex hormone binding globulin (SHBG) and type 2 diabetes mellitus (T2DM) in an Uighur population. One hundred and fourteen T2DM male patients (with a history of diabetes or diagnosed as diabetic by the oral glucose tolerance test) and 173 healthy males from the Uighur ethnic group were included in the study to test the following SNPs of SHBG: rs727428, rs1799941, rs6259, rs6257, rs858521, rs858518, rs3760213, and rs11078701. The body mass index (BMI), blood pressure, and waist circumference, and lipid, glucose, HbA1c, insulin, HOMA-IR, testosterone, and SHBG levels of enrolled individuals were measured. We used the t-test or rank sum test and Chi-square test to analyze the difference and compare numeration data, respectively, between the case and control groups. Comparisons among multiple groups were carried out using analysis of variance, and the correlation between variables was determined by nonparametric Spearman rank correlation analysis; multivariate logistic regression analysis was used to assess the risk of abnormal glucose in the two groups. There was a significant difference (P < 0.05) in BMI, blood pressure, and waist circumference, and lipid, glucose, HbA1c, insulin, and HOMA-IR levels between the case and control groups. The risk factors for diabetes included testosterone (P = 0.042) and SHBG (P = 0.001). The distribution of rs858521 (P = 0.001), rs1799941 (2.3%, P = 0.032), rs6259 (2.5%, P = 0.040), and rs727428 (3.4%, P = 0.016) was significantly different between the case and control groups (P < 0.05). In the control group, there was linkage disequilibrium (LD) between rs727428 and rs6259, while in the case group LD was found among rs858518, rs3760213, rs1799941, and rs6257. The frequency of rs858518-rs3760213-rs1799941-rs6257 haplotype TCGC was significantly different between the two groups (P = 0.033). Both testosterone and SHBGwere found to be risk factors of diabetes in the Uighur population, and SNPs of SHBG may contribute to T2DM.