Genetic linkage methods for diseases with complex inheritance are based on assessment of allele sharing between affected relative pairs, but such methods have low power to detect genes with moderate effects. This may explain the difficulty in replication for many of the putative loci for type 2 diabetes. To enhance power to detect diabetes-susceptibility genes, some investigators have performed quantitative-trait linkage studies for diabetes-related traits, including measures of glycemia, insulin sensitivity, insulin secretion, obesity, lipidemia, and blood pressure. These linkage studies have not provided stronger or more consistent evidence for linkage than studies of diabetes affection status, but have identified several loci that may play an important role in the physiologic processes related to the development of type 2 diabetes.