Redondo MJ, Sosenko J, Libman I, et al. - Given that multiple islet autoantibody positivity usually precedes clinical (stage 3) type 1 diabetes (T1D), researchers tested the assumption that people who develop stage 3 T1D with only a single autoantibody have unique metabolic differences. Participants in the study were autoantibody-positive relatives who developed stage 3 T1D (at median age 12.4 years, range = 1.4–58.6) and had autoantibody data close to clinical diagnosis (n = 786, 47.4% male, 79.9% non-Hispanic white). Single autoantibody at diagnosis of stage 3 T1D was related to older age and insulin resistance possibly mediated by elevated BMI relative to multiple autoantibody positivity, indicating heterogeneous pathogenesis of the disease. Such variations are potentially relevant for prevention and treatment of T1D.