GCG and type 2 diabetes mellitus: Lastly, knockdown of ADCY5 and Tcf7l2, genes identified by GWAS as potentially harbouring single nucleotide polymorphisms (SNPs) increasing T2DM risk, led to marked decreases in beta cell–beta cell coordination (Hodson et al. 2014, Mitchell et al. 2014), as well as impaired glucose- and GLP-1-stimulated insulin secretion.