Based on more specific analysis of T2D phenotypes, implicated genes have been clustered by risk alleles associated with the following: (i) primary effects on insulin sensitivity (PPARG, KLF14, IRS1 and GCKR); (ii) reduced insulin secretion and fasting hyperglycaemia (MTNR1B and GCK); (iii) defects in insulin processing (ARAP1); and (iv) insulin processing and secretion without a detectable change in fasting glucose levels (TCF7L2, SLC30A8, HHEX/IDE, CDKAL1 and CDKN2A/2B) [31]. This evidence concerns the gene SLC30A8 and type 2 diabetes mellitus.