SST and type 1 diabetes mellitus: The proportion of insulin+/somatostatin+ cells was 0%, 0.4% and 0% in insulin-containing islets of control subjects, insulin-containing islets of persons with T1D, and insulin-deficient islets, respectively, and was significantly lower in insulin-deficient islets than in insulin-containing islets of persons with T1D (Table 3, Figure S2a), which was due to the absence of true β-cells in insulin-deficient islets.