Until recently, progress in identification of the genetic variants influencing predisposition to common forms of diabetes and obesity has been slow, a sharp contrast to the large number of genes implicated in rare monogenic forms of both conditions. Recent advances have transformed the situation, however, enabling researchers to undertake well-powered scans able to detect association signals across the entire genome. For type 2 diabetes, the six high-density genome-wide association studies so far performed have extended the number of loci harboring common variants implicated in diabetes susceptibility into double figures. One of these loci, mapping to the fat mass and obesity associated gene (FTO), influences diabetes risk through a primary effect on fat mass, making this the first common variant known to influence weight and individual risk of obesity. These findings offer two main avenues for clinical translation. First, the identification of new pathways involved in disease predisposition-for example, those influencing zinc transport and pancreatic islet regeneration in the case of type 2 diabetes-offers opportunities for development of novel therapeutic and preventative approaches. Second, with continuing efforts to identify additional genetic variants, it may become possible to use patterns of predisposition to tailor individual management of these conditions.