Wang CY, et al. - Among 4,607 women with primary breast cancer and 23,035 age-matched controls without breast cancer, researchers ascertained if postmenopausal women who develop breast cancer were at a higher risk of developing diabetes mellitus (DM). The Taiwan National Health Insurance Research Database for women aged ≥ 55 years (postmenopausal) with primary breast cancer diagnosis was searched from 2001 to 2015. Among breast cancer patients receiving hormone therapy, the incidence of DM at 1 year was 1.22-fold higher than for those receiving no hormone therapy, but without statistical significance. Findings suggested that postmenopausal women with breast cancer were at a higher risk of developing DM, irrespective of receiving hormone therapy. To improve related outcomes, they should be monitored closely for early diagnosis and therapeutic intervention.