One approach that is used to identify disease susceptibility genes is based candidate genes.  Candidate genes are selected because they are thought to be involved in pancreatic beta cell function, insulin action / glucose metabolism, or other metabolic conditions that increase T2D risk (e.g., energy intake / expenditure, lipid metabolism).  To date, more than 50 candidate genes for T2D have been studied in various populations.  However, results for essentially all of the them has been conflicting.  Possible explanations for the divergent findings include small sample sized, differences in T2D susceptibility across ethnic groups, variations in environmental exposures, and gene-gene interactions.  Because of the current controversy, we will discuss only a few of the most promising candidate genes.  These include PPARγ, ABCC8, KCNJ11 and CALPN10.