Oskar S, et al. - Whether type II diabetes mellitus (T2DM) and gestational diabetes mellitus (GDM) are associated with higher mammographic breast density in a mostly racial/ethnic minority sample was investigated. Between 2012 and 2016, digital mammograms, anthropometric measures, and interview data from 511 racially diverse women recruited during mammography appointments were collected. This investigation did not find relationships between T2DM and/or GDM and a higher amount of mammographically dense breast tissue, inferring that the mechanism connecting diabetes with breast cancer risk may not include mammographic breast density in midlife.