The IRAS was renewed in August 1999 through July 2005 as the IRAS Family Study. The purpose was to identify the genetic determinants of insulin resistance and abdominal obesity and to determine the extent to which insulin resistance, visceral adiposity, and metabolic cardiovascular disease risk factors share common genetic influences. Families of African-American and Hispanic background were enrolled using participants of the original IRAS study as index cases. Approximately 1,280 additional family members were recruited to the study for a total of 1,440 participants. Insulin resistance was measured using the frequently sampled intravenous glucose tolerance test, and abdominal obesity was measured using computed tomography. Metabolic cardiovascular disease risk factors were also assessed. A panel of 370 micro satellite markers were genotyped to provide data for a genome-wide scan to detect chromosomal regions containing quantitative trait loci (QTLs) that influenced phenotypic variation for insulin resistance and visceral adiposity.