We performed immune cell phenotyping using cryopreserved samples collected from participants of the Cardiovascular Health Study (CHS), a U.S. community‐based cohort of adults ages 65 and older, and investigated the longitudinal associations of naive, memory and differentiated/senescent CD4+ and CD8+ T cell and memory B cell subsets with incident DM over 11.5 years of follow‐up. Here, CD8A is linked to diabetes mellitus.