The genetic component of the more common form of type 2 diabetes is probably complex and involves the interactions of multiple genes and environmental factors. Until recently, only a few loci were known, but this is changing rapidly as a result of the development of high-density genotyping arrays that have permitted genome-wide association studies. This book provides state of the art information and reviews the evidence that insulin resistance has a genetic basis. The genetic component of the more common form of type 2 diabetes is probably complex and involves the interactions of multiple genes and environmental factors. This book provides new insights into the identification of novel genes and pathways that lead to this complex disease. Progress to date toward identifying specific gene variants is reviewed.