Stomach stem cells are accessible by biopsy and propagate robustly in culture, offering an invaluable resource for autologous cell therapies. Here we describe a detailed protocol to isolate, expand, engineer and differentiate human gastric stem cells (hGSCs) into pancreatic islet-like organoids containing abundant gastric insulin-secreting (GINS) cells that resemble beta-cells in molecular hallmarks and function. Sequential activation of the inducing factors NGN3 and PDX1-MAFA led hGSCs onto a novel differentiation path, including endocrine progenitor and GINS precursor, before adopting beta-cell identity, at efficiencies close to 70%. GINS organoids acquired glucose-stimulated insulin secretion in 10 days post differentiation.