A Rare Case of Presumed Insulin-Like Growth Factor 2 (IGF-2)-Mediated Hypoglycemia

Non-diabetic hypoglycemia is an uncommon yet potentially life-threatening medical disorder in adults. An atypical cause is non-islet cell tumor hypoglycemia (NICTH), frequently mediated by insulin-like growth factor 2 (IGF-2) released by mesenchymal tumors, including gastrointestinal stromal tumors (GISTs). We discuss the case of a 75-year-old male who exhibited recurring bouts of altered sensorium, disorientation, and excessive sweating during a three-month period, all of which resolved upon food consumption. Preliminary assessments indicated hypoglycemia (capillary blood glucose 35-40 mg/dL) without any prior history of diabetes, insulin, or sulfonylurea administration. A monitored 72-hour fasting test revealed hypoglycemia (capillary blood glucose (CBG) 42 mg/dL), suppressed insulin (<0.20 µIU/mL), and C-peptide (0.12 ng/mL), thereby excluding insulinoma and factitious hypoglycemia. Imaging identified an intra-abdominal mass, and histopathological analysis corroborated the diagnosis of gastrointestinal stromal tumor (GIST). The clinical presentation was suggestive of a presumed IGF-2-mediated NICTH. In light of the lack of metastatic dissemination and the patient's advanced age, targeted therapy with imatinib was commenced, leading to the elimination of hypoglycemia episodes. This case underscores the necessity of incorporating NICTH into the differential diagnosis of hypoglycemia in non-diabetic individuals, particularly when a tumor is present. Timely identification and focused intervention of the underlying neoplasm can result in positive outcomes.