The aims of this study are: (1) to assess if the previously reported PARL missense Val262Leu polymorphism (not genotyped on commercial arrays) is associated with population fasting plasma insulin levels and (2) to conduct a comprehensive T2D candidate gene association and functional expression study of the linkage disequilibrium (LD) region (approximately 185,000–185,250 kb, Build 36) that includes PARL and neighbouring ABCC5. Here, INS is linked to type 2 diabetes mellitus.