Introduction: Insulinoma during pregnancy is exceedingly rare, with fewer than 30 cases reported worldwide. Diagnosis is often delayed due to overlapping physiological and gestational symptoms, posing significant risks to both mother and fetus. Case: We report a case of a 36-year-old G4P2 + 1 female presenting at 7 weeks’ gestation with recurrent symptomatic hypoglycemia initially suspected due to poor oral intake. She returned at 12 weeks with persistent neuroglycopenic symptoms and weight loss. Biochemical evaluation demonstrated inappropriately non-suppressed insulin and C-peptide levels during hypoglycemia, raising suspicion for endogenous hyperinsulinemia. Imaging with magnetic resonance imaging identified a 2.3 × 2.5 cm pancreatic lesion consistent with insulinoma. A multidisciplinary team (MDT) approach involving Internal Medicine, Endocrinology, Obstetrics and Gynecology (Maternal-Fetal Medicine), Hepatobiliary Surgery, and Radiology guided management. Due to concerns regarding surgical and ablative risks during pregnancy, medical therapy with octreotide was initiated, achieving partial glycemic control. The pregnancy was complicated by fetal growth restriction, necessitating delivery at 34 weeks. Postpartum, the patient underwent endoscopic ultrasoundguided radiofrequency ablation (EUS-RFA), requiring two sessions before achieving glycemic stabilization. Conclusion This case highlights the diagnostic challenges of insulinoma in pregnancy and underscores the importance of MDTguided individualized management. It also illustrates the limitations of EUS-RFA and medical therapy, particularly in larger tumors, and raises important considerations regarding fetal outcomes.
Female ; Pregnancy ; Insulinoma ; Hypoglycemia

Introduction: A negative computed tomography (CT) scan does not preclude an insulinoma, as small lesions frequently remain undetected on conventional imaging. This case highlights the indispensable role of endoscopic ultrasound (EUS)— not just for localizing occult tumors, but as a definitive, minimally invasive therapeutic alternative to high-risk surgical resection. Case: A 39-year-old female with underlying hypertension presented with a 5-month history of predominantly fasting hypoglycemia (glucose <3.0 mmol/L) and neuroglycopenic symptoms, fulfilling Whipple’s triad. A supervised 72-hour fast confirmed endogenous hyperinsulinemic hypoglycemia at 31 hours, with a nadir glucose of 1.4 mmol/L, insulin 116 pmol/L, and C-peptide 821 pmol/L. Notably, contrastenhanced CT of the pancreas was reported as normal. To overcome this, EUS was performed, successfully identifying a hidden 19 × 18 mm lesion in the head of the pancreas, intimately abutting the main pancreatic duct. Despite medical therapy with diazoxide and strict dietary modifications, her hypoglycemia remained refractory. Given the tumor’s proximity to the main pancreatic duct, surgical enucleation carried a prohibitively high risk of complications. Consequently, she underwent EUS-guided radiofrequency ablation (RFA). Immediate post-procedure outcomes demonstrated near-complete resolution of the hypoglycemic episodes. Diazoxide was subsequently stopped. Outpatient continuous glucose monitoring confirmed sustained normoglycemia and marked symptom resolution, with no procedure-related complications. Conclusion The absence of a pancreatic lesion on CT demands persistent clinical suspicion in cases of biochemically proven hypoglycemia. EUS remains paramount for detecting occult lesions missed by standard imaging. Importantly, EUSRFA serves as a highly effective, tissue-sparing alternative to surgical resection for insulinomas, especially when conventional surgery poses prohibitive anatomical risks.
Insulinoma ; Tomography, X-Ray Computed

Introduction: Pancreatic neuroendocrine tumors (PNETs) are rare, comprising less than 3% of all pancreatic neoplasms. These tumors are broadly classified as functioning or nonfunctioning. Insulinoma is the most common functioning PNET. Non-functioning PNETs often present significant diagnostic issues and may be misdiagnosed as pancreatic adenocarcinoma, especially when immunohistochemical evaluation is omitted during histological examination. We describe a case of metastatic insulinoma that was misdiagnosed as a poorly differentiated pancreatic adenocarcinoma. Case: A 65-year-old female first presented to a private hospital in 2023 with obstructive jaundice and was found to have a pancreatic head lesion that was causing biliary obstruction. As a result, a biliary stent was placed. She underwent aortocaval lymph node biopsy, and the result showed poorly differentiated pancreatic adenocarcinoma. Nonetheless, she refused surgical and oncological intervention. Even so, she remained clinically stable and maintained good functional status for 2 years. In 2025, she presented to Hospital Canselor Tuanku Muhriz with recurrent hypoglycemia fulfilling Whipple’s triad. The unexpectedly indolent clinical course prompted reassessment of the initial diagnosis. Biochemical evaluation confirmed endogenous hyperinsulinemic hypoglycemia, with inappropriately elevated insulin (11.03 µIU/mL) and C-peptide levels (1,089 pmol/L). Computer tomography of the abdomen revealed multiple hepatic lesions and progressive lymphadenopathy, suggestive of metastatic disease. Re-evaluation of the initial histopathological specimen showed a well-differentiated neuroendocrine tumor (Grade 1, Ki-67 ~2%). Hence, the diagnosis was revised to metastatic insulinoma. She was referred to the hepatobiliary surgical team for surgical debulking, but the procedure was deemed highrisk and likely to have high mortality due to the extent of the disease. She was managed with diazoxide and longacting somatostatin analogues for glycemic control. Conclusion This case highlights the critical importance of diagnostic vigilance when evaluating pancreatic neoplasms. Persistent or unexplained clinical courses, especially when endocrine symptoms arise, should prompt thorough reassessment. Immunohistochemical confirmation is essential to avoid misdiagnosis and ensure optimal patient management.
Adenocarcinoma ; Insulinoma ; Pancreatic Neoplasms

Introduction: Insulinoma is a rare functioning pancreatic neuroendocrine tumor and the most common cause of endogenous hyperinsulinemic hypoglycemia. Although biochemical confirmation is usually straightforward, tumor localization may be difficult when lesions are small and not detected on conventional cross-sectional imaging. In such cases, endoscopic ultrasound (EUS) plays an important role in identifying occult lesions and facilitating definitive treatment. Case: A 52-year-old female was admitted in April 2025 with recurrent seizures secondary to hypoglycemia for 3 years, with increasing frequency over time. She fulfilled Whipple’s triad, with documented capillary glucose of 1.8 mmol/L during an episode and symptom resolution following glucose administration. A supervised prolonged fasting test confirmed endogenous hyperinsulinemic hypoglycemia, with plasma glucose 1.4 mmol/L, insulin 122 pmol/L, and C-peptide 1,010 pmol/L. Short Synacthen test demonstrated adequate adrenal reserve. Due to persistent hypoglycemia, she required high-dose diazoxide. Contrast-enhanced computed tomography abdomen did not reveal a pancreatic lesion but incidentally detected a right ovarian teratoma. She underwent total abdominal hysterectomy and bilateral salpingo-oophorectomy in June 2025, with histopathology confirming a mature cystic teratoma without malignancy. However, hypoglycemic episodes persisted. Further evaluation with EUS in July 2025 identified a highly vascular isoechoic 8 × 8 mm lesion in the pancreatic body. Fine-needle biopsy confirmed a well-differentiated neuroendocrine tumor (WHO grade 1) with Ki-67 index of 2%. She subsequently underwent EUSguided radiofrequency ablation in August 2025. Follow-up EUS in December 2025 showed post-ablation change, and her hypoglycemic episodes resolved completely, allowing diazoxide to be discontinued. Conclusion This case highlights the diagnostic challenge of occult insulinoma in the presence of negative conventional imaging. EUS was pivotal for tumor localization and tissue diagnosis, while EUS-guided radiofrequency ablation provided effective minimally invasive treatment in a carefully selected patient.
Insulinoma ; Tomography, X-Ray Computed

Background: Insulinoma is one of the causes of recurrent hypoglycemia, one of the chief complaints for emergency department admission. The gold standard in diagnosing insulinoma is a 72-hour fasting test which is inconvenient and inefficient as it requires hospitalization. Research has found that measurement of insulin and C-peptide during OGTT may help diagnose insulinoma. We aimed to assess the diagnostic value of OGTT in diagnosing insulinoma. Methodology: The literature search was conducted on 19 August 2022 using several databases (MEDLINE, Scopus, Embase, and ScienceDirect). All studies that measured OGTT as diagnostic tools in diagnosing insulinoma and 72-hour fasting test as reference standard were included. The quality assessment of the selected studies was based on the Centre of Evidence-Based Medicine University of Oxford and the Quality Assessment of Diagnostic Accuracy-2 tool (QUADAS-2). Analysis of the included studies was performed qualitatively. This study was registered on PROSPERO (CRD42022360205). Results: A total of two case-control studies (106 patients) were included, which were at risk of bias and low concern of applicability. Both studies demonstrated that the combination of insulin and C-peptide levels measured during OGTT had high specificity, sensitivity, positive predictive value, and negative predictive value in diagnosing insulinoma compared to the reference standard. A logistic regression model of 8.305 – (0.441 × insulin 2-h/0-h) – (1.679 × C-peptide 1-h/0-h) > 0.351 has the highest diagnostic value in one study (AUC 0.97, Sensitivity 86.5%, Specificity 95.2%, PPV 94.1, NPV 88.9). Conclusion The measurement of 0-h and 2-h insulin and C-peptide levels during 2-h OGTT was found in two small case-control studies with a total of 106 patients to have good sensitivity and specificity. However, due to these limitations, future research is still needed to validate the potential use of OGTT for the diagnosis of insulinoma.
Insulinoma ; Glucose Tolerance Test

This study established a pyroptosis injury model by stimulating insulinoma cells(INS-1) of rats with high glucose(HG) and observed the impact of additional ethanol(ET) exposure on cell pyroptosis, as well as the intervention effect of salidroside(SAL). INS-1 cells were cultured and divided into a normal control group(NG), an HG group, an HG + ET(100 mmol·L~(-1)) group, and an HG + ET + SAL(1-100 μmol·L~(-1)) group. After 72 hours of treatment, cell viability was assessed using the cell counting kit-8(CCK-8) assay. The number of pyroptotic bodies was observed under a microscope. Western blot was used to detect changes in the intracellular Nod-like receptor protein 3(NLRP3)/gasdermin D(GSDMD) signaling pathway and adenosine monophosphate-activated protein kinase(AMPK) activity. A fluorescence probe was used to detect changes in intracellular reactive oxygen species(ROS) levels. Time-resolved fluorescence resonance energy transfer(TR-FRET) technology was employed to observe the effect of SAL on recombinant AMPK protein kinase activity in vitro. The results showed that compared to the NG group, HG exposure induced an increase in the number of pyroptotic bodies, elevated ROS levels, and activation of the NLRP3/GSDMD signaling pathway in INS-1 cells. Compared to the HG group, HG + ET exposure further exacerbated these changes. Compared to the HG + ET group, SAL dose-dependently increased cell viability, reduced the formation of pyroptotic bodies in INS-1 cells, and inhibited excessive ROS production, overactivation of the NLRP3/GSDMD signaling pathway, and the decrease in AMPK activity. TR-FRET experiments indicated that SAL could directly activate AMPK. When INS-1 cells were pretreated with an AMPK inhibitor, the effects of SAL on increasing cell viability, alleviating the formation of pyroptotic bodies, and inhibiting excessive ROS production were abolished. These results suggest that SAL can alleviate HG combined with ET-induced exacerbation of INS-1 pyroptosis by activating AMPK.
Pyroptosis/drug effects* ; Animals ; Rats ; Glucose/metabolism* ; Insulinoma/metabolism* ; Ethanol/pharmacology* ; Reactive Oxygen Species/metabolism* ; Glucosides/pharmacology* ; Phenols/pharmacology* ; Cell Line, Tumor ; Signal Transduction/drug effects* ; NLR Family, Pyrin Domain-Containing 3 Protein/genetics* ; Cell Survival/drug effects* ; AMP-Activated Protein Kinases/metabolism* ; Phosphate-Binding Proteins/genetics*

Insulinoma-associated protein-2 (IA-2) is a transmembrane glycoprotein belonging to the tyrosine phosphatase-like protein family as well as an important autoantigen in the diagnosis of type 1 diabetes. IA-2 products have been marketed in Europe and the United States. At present, commercially available IA-2 antigens are either the recombinant IA-2ic domain or the IA-2 naturally extracted from bovine islets. However, the recombinant IA-2 antigen displays weak positive in clinic practice, which often results in occasional detection failures, thus cannot completely replace the naturally extracted IA-2 antigen. In this study, an HEK293 expression system was used to explore the production of recombinant IA-2. An IA-2 transmembrane fragment (IA-2 TMF) located at amino acid position 449-979, also known as the natural membrane protein form of IA-2, was produced in HEK293 through transfection, and both the expression conditions and dissolution conditions of the membrane protein were also optimized. The purified membrane protein yield was 0.78 mg/L cell culture. Subsequently, the antigen activity of IA-2 TMF was compared with RSR rhIA-2 through enzyme linked immunosorbent assay. The serum of 77 type 1 diabetes patients and 32 healthy volunteers were detected. Receiver operating characteristic curve (ROC) curve was used to characterize the sensitivity and specificity of the test results. The results showed that the sensitivity of IA-2 TMF was 71.4% (55/77), while the sensitivity of RSR rhIA-2 was 63.6% (49/77), and the specificity of both antigens were all 100%. There was no significant difference in specificity between the two antigens, but the sensitivity of IA-2 TMF was appreciably better than that of the imported gold standard RSR rhIA-2 antigen. In conclusion, the recombinant IA-2 TMF produced in HEK293 cells can be used as a raw material to develop in vitro diagnostic reagents for type 1 diabetes.
Humans ; Animals ; Cattle ; HEK293 Cells ; Insulinoma ; Diabetes Mellitus, Type 1/genetics* ; Recombinant Proteins ; Membrane Proteins ; Pancreatic Neoplasms

Objective To determine the appropriate averaging strategy for pancreatic perfusion datasets to create images for routine reading of insulinoma.Methods Thirty-nine patients undergoing pancreatic perfusion CT in Peking Union Medical College Hospital and diagnosed as insulinoma by pathology were enrolled in this retrospective study.The time-density curve of abdominal aorta calculated by software dynamic angio was used to decide the timings for averaging.Five strategies,by averaging 3,5,7,9 and 11 dynamic scans in perfusion,all including peak enhancement of the abdominal aorta,were investigated in the study.The image noise,pancreas signal-to-noise ratio(SNR),lesion contrast and lesion contrast-to-noise ratio(CNR)were recorded and compared.Besides,overall image quality and insulinoma depiction were also compared.ANOVA and Friedman's test were performed.Results The image noise decreased and the SNR of pancreas increased with the increase in averaging time points(all P<0.001).The lesion contrast(69.81±41.35)averaged from 5 scans showed no significant difference compared with that(72.77±45.25)averaged from 3 scans(P=0.103),both of which were higher than that in other groups(all P≤0.001).The lesion CNRs of the last four groups showed no significant difference(all P>0.99)and were higher than that of the first group(all P<0.05).There was no significant difference in overall image quality among the 5 groups(P=0.977).Conclusions Image averaged from 5 scans showed moderate image noise,pancreas SNR and relatively high lesion contrast and lesion CNR.Therefore,it is advised to be used in image averaging to detect insulinoma.
Contrast Media ; Humans ; Insulinoma/diagnostic imaging* ; Pancreas/diagnostic imaging* ; Pancreatic Neoplasms/diagnostic imaging* ; Perfusion ; Radiographic Image Interpretation, Computer-Assisted ; Reading ; Retrospective Studies ; Signal-To-Noise Ratio

To prospectively evaluate the correlation between intravoxel incoherent motion (IVIM)-derived parameters and CT perfusion parameters as well as the pathological grade in insulinoma. A total of 55 patients with suspected insulinoma undergoing IVIM and CT perfusion scans were prospectively enrolled. The images were post-processed to obtain IVIM parameters including apparent diffusion coefficient (ADC),diffusion (D),perfusion correlated diffusion (D*),and f,and CT perfusion parameters including blood flow (BF),blood volume (BV),and permeability (PM). The pathological specimens were stained to obtain pathological parameters including the grading,ki-67 index,and the mitotic count. The IVIM derived parameters of normal pancreas including head,body,and tail as well as that of the pancreatic insulinoma were compared. The correlation between IVIM parameters and CT perfusion parameters as well as the pathological parameters was analyzed. ADC and D values of pancreatic tail were significantly lower than those of the pancreatic head and neck (all <0.001). There were significant differences in all IVIM parameters between insulinoma and normal pancreas (all <0.001). The ADC and f value of the normal pancreas was positively correlated with BF (=0.437,=0.003;=0.357,=0.010). There is no correlation between the remaining IVIM parameters and the CT perfusion parameters as well as between IVIM parameters and pathological parameters (all >0.05). IVIM parameters differ at different anatomical parts of normal pancreas. IVIM parameters can distinguish normal pancreatic parenchyma from insulinoma. The ADC value is weakly correlated with BF.
Diffusion Magnetic Resonance Imaging ; Humans ; Insulinoma ; diagnostic imaging ; Motion ; Pancreatic Neoplasms ; diagnostic imaging ; Reproducibility of Results ; Tomography, X-Ray Computed

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disorder. A 44-year-old man visited second Xiangya Hospital, Central South University due to hypoglycemia. He was eventually diagnosed as MEN1. A novel homozygous frameshift for c.640-643delCAGA (p.V215Mfs*13) of MEN1 gene was identified in the patient. After MDT (Multiple Disciplinary Team), open bilateral exploration with total parathyroidectomy and autotransplantation as well as partial pancreatectomy excision of all the macroscopic pancreatic tumors were performed at the same time. The patient recovered well. Individualized diagnosis and treatment are important for MEN1 patients.
Adult ; Humans ; Insulinoma ; Male ; Multiple Endocrine Neoplasia Type 1 ; Pancreatic Neoplasms ; Parathyroid Neoplasms ; Parathyroidectomy