This study is testing a new imaging agent to find insulinoma, a rare tumor in the pancreas that causes low blood sugar. Traditional scans often miss these tiny tumors. The new agent, called **[68Ga]Ga-HBED-CC-PEG6-Exendin-4**, is designed to better detect insulinomas by targeting a protein called GLP1R, which is found in high amounts on these tumors.

Twenty adults with suspected insulinoma will join the study. Participants will get two free PET/CT scans in one week with two different tracers: one new and one old. The scans are safe and have low radiation. Within a month of the scans, participants will have surgery or a biopsy to confirm the tumor's presence and compare scan results. Participants won't pay for the scans and will receive a report for their doctor.

• Duration: Two scans within one week; surgery or biopsy within one month.
• Risks: Minor pain or allergic reactions; rare effects from Exendin-4.
• Benefits: Improved tumor detection to aid treatment planning.