The pancreas is a key metabolic regulator. When pancreatic beta cells cease producing enough insulin, blood sugar levels rise dangerously—a phenomenon known as hyperglycemia—thus triggering diabetes. After discovering that other mature pancreatic cells can adapt and partly compensate for the lack of insulin, a team from the University of Geneva (UNIGE) demonstrates that the stem cells from which beta cells are derived are only present during embryonic development. This discovery puts an end to a long-standing controversy about the hypothetical existence of adult pancreatic stem cells that would give rise to newly differentiated hormone-producing cells after birth. The scientists also succeeded in precisely defining the ‘identity card’ of pancreatic endocrine cells, which is a promising tool for the production of replacement insulin-secreting cells. These results can be read in Cell Reports and Nature Communications.