In the present study, we have, therefore, utilized these unique samples and applied an optimized triple-label immunohistochemical protocol for comparing the localization of GPX1 in beta and alpha cells and for estimating its level and relative expression in the two cell-types in high-quality human pancreatic sections from diabetic and non-diabetic deceased donors, supplied by the Network for Pancreatic Organ Donors with Diabetes (nPOD) and the Exeter Archival Diabetes Biobank (EADB) (Morgan and Richardson 2018; Pugliese et al. 2014). The gene discussed is GPX1; the disease is diabetes mellitus.