GC gene polymorphisms found with type 2 diabetes and low vitamin D status among rural Chinese in Henan province

Accumulating evidence suggests that vitamin D may be involved in the pathogenesis of type 2 diabetes (T2D). Group-specific component (GC) gene is the most important transporter of vitamin D and plays a regulatory role in vitamin D metabolism. We aimed to evaluate the association of GC gene polymorphisms with T2D susceptibility and vitamin D status in the Chinese rural population.

A total of 1372 subjects were eligible in this cross-sectional study. Three SNPs of the GC gene (rs7041, rs4588, and rs2282679) were genotyped by TaqMan probe assays. Logistic regression and Kruskal-Wallis one-way analysis were performed to determine the possible risk genotype for T2D and vitamin D metabolite concentrations, respectively.

The serum 25-hydroxyvitamin D3 [25(OH)D3] and vitamin D binding protein (DBP) concentrations were significantly lower in the T2D group than the non-T2D group. GG genotype carriers of rs7041 (T>G) were more likely to have T2D compared with AA carriers (OR=2.00, 95% CI: 1.19-3.37). Variants of rs4588 (C>A) and rs2282679 (A>C) were associated with a lower risk of T2D under the dominant inheritance model (OR=0.65, 95% CI: 0.48-0.88; OR=0.66, 95% CI: 0.49-0.90, respectively). We further found that non-T2D subjects with the AA genotype of rs4588 had significantly higher 25(OH)D3 concentrations than the CC genotype (p=0.022). In contrast, the T2D cases with the CC genotype of rs2282679 had lower DBP concentrations compared to the AA genotype (p=0.020).

Our study indicates a potential role for GC gene polymorphisms in T2D susceptibility and vitamin D metabolite concentrations in the Chinese rural population.