Genetic polymorphism of glucokinase on the risk of type 2 diabetes and impaired glucose regulation: evidence based on 298,468 subjects.

BACKGROUND: Glucokinase (GCK) is the key glucose phosphorylation enzyme which has attracted considerable attention as a candidate gene for type 2 diabetes (T2D) based on its enzyme function as the first rate-limiting step in the glycolysis pathway and regulates glucose-stimulated insulin secretion. In the past decade, the relationship between GCK and T2D has been reported in various ethnic groups. To derive a more precise estimation of the relationship and the effect of factors that might modify the risk, we performed this meta-analysis. METHODS: Databases including Pubmed, EMBASE, Web of Science and China National Knowledge Infrastructure (CNKI) were searched to find relevant studies. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of association. RESULTS: A total of 24 articles involving 88,229 cases and 210,239 controls were included. An overall random-effects per-allele OR of 1.06 (95% CI: 1.03-1.09; P<10(-4)) was found for the GCK -30G>A polymorphism. Significant results were also observed using dominant or recessive genetic models. In the subgroup analyses by ethnicity, significant results were found in Caucasians; whereas no significant associations were found among Asians. In addition, we found that the -30G>A polymorphism is a risk factor associated with increased impaired glucose regulation susceptibility. Besides, -30G>A homozygous was found to be significantly associated with increased fasting plasma glucose level with weighted mean difference (WMD) of 0.15 (95%: 0.05-0.24, P = 0.001) compared with G/G genotype. CONCLUSIONS: This meta-analysis demonstrated that the -30G>A polymorphism of GCK is a risk factor associated with increased T2D susceptibility, but these associations vary in different ethnic populations.