Insulinoma is a common functional pancreatic neuroendocrine tumor, with high possibility of being misdiagnosed due to complex and changeable symptoms. Making a topical diagnosis and providing patients with the optimal treatment are major challenges in the diagnosis and treatment of insulinoma.

To give a summary of our experience of diagnosis and treatment of insulinoma.

A retrospective design was used. Participants were 15 insulinoma patients who received surgical treatment in Affiliated Hospital of Chengde Medical University from 2009 to 2019. Their clinical data (including clinical presentations, qualitative diagnosis, topical diagnosis, surgical approach, and postoperative conditions) , and follow-up data were summarized.

Thirteen patients had solitary insulinoma, 2 patients had multiple insulinomas. One patient with multiple insulinomas also had multiple neuroendocrine tumor type 1 (MEN-1) . All cases showed Whipple's triad, with an insulin release index (IRI/G) greater than 0.3. All patients had negative results for transabdominal ultrasonography. Fourteen patients had positive results for enhanced pancreatic CT, and the other one with negative results was found with insulinoma by MRI. All patients underwent surgical resection, among whom 9 underwent insulinoma enucleation, 5 underwent a distal pancreatectomy (4 used laparoscopic approach and 1 used open approach) , the MEN-1 patient underwent pylorus-preserving pancreaticoduodenectomy (PPPD) plus distal pancreatectomy. All tumors were pathologically benign. There were 4 cases of postoperative clinically relevant pancreatic fistula (grade B/C) , and there was no perioperative death. Hypoglycemia disappeared after resection in all cases, and no recurrence and new-onset diabetes were found in the follow-up.

Whipple's triad and IRI/G are the main evidence for qualitative diagnosis preoperatively. Contrast-enhanced CT and MRI of the pancreas are the first-line preoperative diagnostic methods, and endoscopic ultrasound is an important supplementary method. Surgical resection is the first-line treatment, and enucleation should be preferred for eligible patients in order to fully preserving pancreatic exocrine and endocrine functions.