To our knowledge, this is the first study to investigate the role of the Hp genotype in cognitive function and decline among elderly African American adults with type 2 diabetes, who are at particularly high risk of developing dementia1,2,3 and other type 2 diabetes complications.6,7 We show that the Hp 1-1 genotype, which is 2-fold (approximately 30%) more prevalent among African American adults than among individuals of white race/ethnicity, was associated with poorer cognitive function and greater cognitive decline than the other Hp genotypes. The gene discussed is HP; the disease is type 2 diabetes mellitus.