Wiley Acta Medica Okayama 2050-0904 11 8 2023 Preoperative detection of functional somatostatin receptors in a patient with an insulinoma e7771 EN Kohei Oguni Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Shinnosuke Fukushima Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Yukichika Yamamoto Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Kou Hasegawa Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Hideharu Hagiya Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Naoko Inoshita Department of Pathology, Moriyama Memorial Hospital Fumio Otsuka Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Octreotide is used in patients with insulinomas to treat hypoglycemia, and somatostatin receptor (SSTR) 2 expression is important for its efficacy. We report a case of insulinoma in a 50-year-old woman that responded to an octreotide test, showed accumulation in somatostatin scintigraphy, and was positive for SSTR2A on immunostaining. No potential conflict of interest relevant to this article was reported.