8394 Increased alpha cells mass in surrounding pancreatic islet in insulinoma patients

Abstract Disclosure: B. Kim: None. H. Park: None. J. Shin: None. K. Kim: None. Background: Insulin is an essential treatment for controlling blood sugar in diabetic patients. However, research on the direct or indirect effects of hyperinsulinemic states on pancreatic islets cell population is limited. We need to determine the morphology of surrounding pancreatic islets in insulinoma patients and changes in the pancreatic islet after insulin administration in mice model. Methods: Insulinoma and pancreatic tissue surrounding the insulinoma were obtained after surgery of a patient diagnosed with insulinoma due to frequent hypoglycemia. For mouse model, we administered short acting insulin for 7 days to 50% pancreatectomized mice, and then removed remnant pancreatic tissue. We performed insulin and glucagon immunofluorescent staining of the patient's insulinoma and surrounding pancreatic tissue and the mouse's pancreatic tissue. Results: In the insulinoma patients, persistent hyperinsulinemia and hypoglycemia was observed in prolonged fasting test. Alpha cells mass was increased in the surrounding pancreatic islets in insulinoma. Also, in the islets of insulin-treated mice, the number of alpha cells were increased, and the number of cells co-stained for both insulin and glucagon increased, and proliferation of alpha cells was observed. Conclusion: Although more research is needed to confirm the mechanism of effects of hyperinsulinemia on the proliferation of alpha cells, hyperinsulinemia is thought to play a role in the stimulation of increasing alpha cell mass and contributing to hyperglucagonemia in early diabetes. Presentation: 6/2/2024