INS and type 1 diabetes mellitus: Following the discovery of type 1 diabetes associated with HLA [1], the insulin (INS) variable number tandem repeat (VNTR) [2], and numerous candidate gene polymorphisms, the development of high-throughput genotyping array technology and analytical methods expanded our knowledge of genetic variation implicated in type 1 diabetes risk (summarised in the Text box ‘Genetics of type 1 diabetes: background’).