Haptoglobin 2-2 Genotype is Associated with Increased Risk of Type 2 Diabetes Mellitus in Northern Chinese

The aim of this study was to investigate the association between haptoglobin (Hp) gene polymorphism and occurrence of type 2 diabetes mellitus (T2DM) in a northern Chinese population. We studied the association of the Hp gene polymorphism with T2DM in 584 unrelated T2DM patients and 690 control subjects with normal glucose tolerance among northern Chinese. The patients were diagnosed in accordance with the guidelines of the American Diabetes Association. The clinical characteristics of the study population were recorded, and the Hp genotype was determined. The frequencies of the genotypes in the group of T2DM patients and the controls were as follows: Hp2-2, 51.7% and 44.1%; Hp2-1, 39.7% and 45.1%; and Hp1-1, 8.6% and 10.9%, respectively. There was significant difference for the genotypic and allelic distribution between the two groups (p = 0.021 and p = 0.007, respectively). Even after readjusting for the confounding effects of age, gender, and body mass index, a significant effect of genotypes on T2DM was still found in the recessive model for the Hp2 allele tested (p = 0.002). Those who had the Hp2-2 genotype had a significantly higher risk for T2DM than those with other genotypes (odds ratio = 1.441, 95% confidence interval = 1.143-1.817). The results showed that the Hp2-2 genotype is associated with increased risk of T2DM in the northern Chinese Han population.