Natriuretic peptides are cardiac-derived hormones that enhance insulin sensitivity and reduce fat accumulation. Low natriuretic peptide levels are associated with increased risk of type 2 diabetes mellitus (DM2); a condition with variable prevalence across racial/ethnic groups. Few studies have examined whether circulating natriuretic peptide levels and their response to preventive interventions for DM2 differ by race/ethnicity. The Diabetes Prevention Program (DPP) is a clinical trial (July 31, 1996- July 31, 2001) that randomized participants to preventive interventions for DM2. Using stored serum samples, we examined N-terminus pro-B-type natriuretic peptide (NT-proBNP) levels in 3,220 individuals (56% white; 19% African-American; 15% Hispanic; 5% American-Indian; 5% Asian). The influence of race/ethnicity on NT-proBNP concentrations at baseline and after two years of treatment with placebo, lifestyle, or metformin was examined with multivariable-adjusted regression. At baseline, NT-proBNP differed significantly by race (P