In contrast, over 90% of patients with spontaneous T1D are autoantibody positive at diagnosis and many display evidence of CD138-expressing plasma cells in T/B cell clusters within the pancreas (figure 2I and online supplemental figure S5A).19, 22 Comparison of B cells found within the islets and PBMCs showed enrichment towards different subsets, with naïve B cells being more common in the periphery than the islets (online supplemental figure S5B). This evidence concerns the gene SDC1 and type 1 diabetes mellitus.