Using activation‐induced markers to identify, quantify, and functionally characterize Spike‐specific CD4+ and CD8+ T cells after SARS‐CoV‐2 vaccination, we show defects in T cell memory maintenance and an IL‐10 and IL‐13‐dominated T cell response in people with diabetes, indicating an unfocused, tolerogenic phenotype. Here, CD8A is linked to diabetes mellitus.