The unbiased approach of genome-wide linkage analysis has shown evidence for linkage of type 2 diabetes mellitus to the chromosome 1q21–25 region in at least eight independent studies. More than 26 candidate genes have already been evaluated, but to date none explain the evidence for linkage in this gene-dense region. Considerable data suggest that multiple genes account for this linkage result. The search for these genes is now the focus of an international consortium of groups reporting linkage of type 2 diabetes to this region of chromosome 1q21–q25.