Persistent Hyperinsulinemic Hypoglycemia After Insulinoma Surgery: Diagnostic Impact of GLP-1 Receptor PET/CT After Negative Conventional Imaging.

BACKGROUND

Localization of recurrent or residual insulinoma may be particularly challenging in postoperative setting, especially in the presence of postoperative anatomical distortion and inconclusive conventional imaging.

CASE PRESENTATION: A 71-year-old man developed recurrent endogenous hyperinsulinemic hypoglycemia following apparently curative surgical enucleation of a pancreatic insulinoma. The postoperative course was complicated by intra-abdominal hemorrhage and pseudocyst formation, resulting in marked anatomical distortion. Despite persistent biochemical evidence of insulinoma recurrence, serial contrast-enhanced computed tomography (CT) and 68Ga-DOTATOC PET/CT failed to identify residual disease. Subsequent glucagon-like peptide-1 receptor (GLP-1R) imaging with 68Ga-NODAGA-Exendin-4 PET/CT demonstrated focal tracer uptake in the pancreatic head, highly suggestive of recurrent or residual insulinoma. Endoscopic ultrasound (EUS) subsequently confirmed a small lesion in the uncinate process, which was successfully treated with EUS-guided radiofrequency ablation (EUS-RFA). Following the procedure, hypoglycemic episodes resolved, with normalization of glucose, insulin, and C-peptide levels and no signs of recurrence at follow-up.

CONCLUSION

This case highlights the clinical value of GLP-1 receptor PET/CT for localizing insulinoma in the context of negative conventional or somatostatin receptor (SSTR)-based imaging. Accurate functional localization may directly guide minimally invasive therapeutic interventions and help avoid high-risk reoperative pancreatic surgery.