The goal of this observational study is to evaluate the diagnostic value of ¹⁸F-Exendin-4 PET/CT imaging in renal insulinoma. Participants will undergo clinical evaluation and ¹⁸F-Exendin-4 PET/CT examination.

Early detection, precise diagnosis, and accurate localization are key to the effective management of insulinoma, the most common functional pancreatic neuroendocrine tumor, which is predominantly benign. Histopathological examination remains the diagnostic gold standard, but invasive procedures such as biopsy carry risks of bleeding and hematoma, while rarer complications like infection or pancreatic fistula may also occur. Therefore, there is an urgent clinical need for a highly accurate, non-invasive diagnostic method.

The glucagon-like peptide-1 receptor is overexpressed in insulinomas, making GLP-1R-targeted imaging a major focus in the molecular imaging of this disease. Exendin-4, an analog of GLP-1R agonists, has been shown to specifically bind to GLP-1R when labeled with ⁶⁸Ga, enabling targeted diagnosis of insulinoma. However, compared to ⁶⁸Ga, ¹⁸F offers significant advantages. Although ¹⁸F-labeled exendin-4 has been explored in preclinical studies, its clinical translation has not yet been reported. Therefore, investigating the imaging performance of ¹⁸F-exendin-4 PET/CT in insulinoma is of high clinical relevance.

Inclusion Criteria:

• biochemically confirmed hyperinsulinemic hypoglycemia (plasma glucose < 3.0 mmol/L, insulin > 3 μIU/mL, C-peptide > 0.6 ng/mL)
• surgical or biopsy-confirmed insulinoma or non-insulinoma pancreatogenous hypoglycemia syndrome, with definitive clinical diagnosis at discharge and comprehensive evaluation for hypoglycemia etiology during hospitalization.

Exclusion Criteria:

• unknown etiology of hypoglycemia at last follow-up
• patients clinically diagnosed with insulinoma but without subsequent surgical intervention or biopsy

Patients with diagnosed or highly suspected insulinoma.