Shortly after the initial cloning of ZnT8, a polymorphism in the SLC30A8 gene giving rise to a non-conservative amino acid substitution in the ZnT8 transporter was shown to be strongly associated with type 2 diabetes [3]; this association was subsequently replicated in numerous (e.g., [4]–[7]) but not all [38] genome-wide association analyses. This evidence concerns the gene SLC30A8 and type 2 diabetes mellitus.