Abstract

An association between the IRS-1 Gly972Arg and IRS-2 Gly1057Asp polymorphisms and type 2 diabetes mellitus (T2DM) in different ethnic groups is controversial. We aimed to identify the association of these polymorphisms with T2DM in the Kurdish ethnic group of Iran. Study groups included 336 T2DM and 341 normoglycemic subjects. Genotyping was determined by polymerase chain reaction-restriction fragment length polymorphism. Genotypic and allelic frequencies were then evaluated. GR and RR genotypes of IRS-1 Gly972Arg variant gave a higher risk for T2DM (odds ratios OR = 1.76 and OR = 3.86, respectively). IRS-1 Gly972Arg polymorphism was found to be significantly associated with T2DM (OR = 1.63) for the dominant model (GG vs. GR + RR). GD genotypes of the IRS-2 Gly1057Asp variant gave a higher risk for T2DM (OR = 1.63). The dominant model analysis of the IRS-2 Gly1057Asp genotypes (GG vs. GD + DD) also showed an enhanced association with T2DM (OR = 1.69). Among several combinations, GR/GD gave the highest risk for T2DM (OR = 3.1). Other combinations were also significantly associated with T2DM, including, GR/GG (OR = 1.86), RR/GG (OR = 1.76), GG/GD (OR = 1.83), and GG/DD (OR = 2.35). HbA1c, serum triglyceride, and systolic blood pressure were higher in the control subjects with GR + RR genotypes compared with the GG genotype. Among the T2DM subjects, fasting plasma glucose was significantly lower in subjects with the GG genotype in relation to those with the GR + RR genotypes. Normoglycemic subjects carrying GD + DD genotypes of IRS-2 Gly1057Asp variation had a significantly higher fasting plasma glucose and total cholesterol, as compared with those with the GG genotype. Our findings revealed that IRS-1 Gly972Arg and IRS-2 Gly1057Asp polymorphisms are associated with T2DM in the Kurdish ethnic group.