This research protocol is designed to study the genetic basis of Type 2 Diabetes (T2D) in a broad range of populations in the United States and abroad. This project takes advantage of the well established infrastructure and success of Dr. Rotimi s international genetic epidemiology study of T2D funded as an R01 grant by NIDDK while he was at Howard University. This parent project is ongoing in four major ethnic groups in Nigeria (Yoruba and Ibo) and Ghana (Akan and Gaa). At completion in 2013 and given current projections, we anticipate enrolling about 2,000 cases and 2000 controls from the five centers in West Africa (Enugu, Ibadan and Lagos in Nigeria; Accra and Kumasi in Ghana). However, current projection indicates that the enrollment of Yoruba cases and controls will be short by about 300 cases and 300 controls. It is critically important to supplement the enrollment of Yoruba participants from another community in the Ibadan metropolitan area in Nigeria. Therefore, the original goal of the current project is to enroll additional 300 cases of T2D and 300 ethnically matched Yoruba controls to facilitate the conduct of genome-wide association study (GWAS) and candidate gene/loci studies in West Africans. Other current and future projects will increase the number of subjects for future genome-wide association studies (GWAS), linkage disequilibrium (LD) mapping, and functional studies in different ethnically-defined populations. Each project will aim to enroll ethnically balanced cases and controls with the goal of facilitating the conduct of GWAS and candidate gene/loci studies in a broad range of populations. Overall, these studies aim to further (or in some cases be the first) such large-scale efforts to understand the genetic basis of T2D in individuals of varying backgrounds including African and Mexican ancestries. Identified candidate genes/loci will be investigated by re-sequencing and functional studies will be conducted to identify susceptibility variants for diabetes and associated complications including obesity, hypertension, nephropathy, neuropathy and retinopathy. Additionally, these samples will be used to study genetic variation in the context of how participants of different ancestry respond to drugs and other environmental factors and how this variation may have shaped population history. Given past activities, it is also anticipated that this resource will form the basis of multiple collaborations between Dr. Rotimi s lab, several NIH intramural researchers and non-NIH scientists. Each subsequent population that is added to this study over time will use the same procedures that were originally approved for ongoing work among West Africans.