Immune phenotyping provides insight into disease pathogenesis and prognostic markers. Trajectories from age of 4 to 36 weeks were modeled for insulin autoantibodies and for leukocyte subpopulations in peripheral blood from female NOD (n=58) and NOR (n=22) mice. NOD mice had higher trajectories of insulin autoantibodies, CD4⁺and CD8⁺T lymphocytes, B lymphocytes, IgD⁺IgM⁻B lymphocytes, and NK cells and lower trajectories of CD4⁺CD25⁺T lymphocytes, IgM⁺B lymphocytes, granulocytes, and monocytes than NOR mice (allp<0.001). Of these, only the increased IAA trajectory was observed in NOD mice that developed diabetes as compared to NOD mice that remained diabetes-free. Therefore, the profound differences in peripheral blood leukocyte proportions observed between the diabetes-prone NOD mice and the diabetes-resistant mice do not explain the variation in diabetes development within NOD mice and do not provide markers for diabetes prediction in this model.