6774 Recurrent Hypoglycemia In Malignant Insulinoma With Multiple Liver Metastases Successfully Managed With Octreotide

Abstract Disclosure: K. Kim: None. S. Mascarell: None. Introduction: Insulinoma is a rare functional pancreatic neuroendocrine tumor (pNET) with the incidence of 1-4/million person-years. Malignant insulinomas with locoregional invasion or metastases consist 10% among insulinomas. While the treatment of a single insulinoma is surgical resection, treatment of malignant insulinoma requires a comprehensive approach. Due to the low prevalence of the disease, data on therapeutic modalities of malignant insulinomas are limited. We hereby present a case of malignant insulinoma in which recurrent hypoglycemia was successfully managed with octreotide. Case: A 36 year old female diagnosed with grade III well differentiated pNET with multiple metastases to the liver and abdominal lymph nodes 1 year ago was admitted for recurrent hypoglycemic episodes. She reported progressively worsening hypoglycemia for the past 1 month. She was eating every 2 hours including her sleeping hours to prevent hypoglycemia. Due to recurrent hypoglycemia she required hospitalization with IV dextrose. After 13 hours of fasting in the ICU, hypoglycemia due to insulin hypersecretion was confirmed with blood glucose 51 mg/dL and elevated serum insulin 51.11 uIU/mL (1.9-23uIU/mL). She underwent the short octreotide test which showed suppressed insulin (5.25 uIU/mL) 6 hours after receiving 100 mcg of octreotide. She was started on octreotide 50 mcg every 12 hours and monitored for further hypoglycemic episodes. She tolerated octreotide without any side effects including hypoglycemia. She was discharged home with a continuous glucose monitor (CGM) and transitioned to intramuscular lanreotide 20mg injections every 4 weeks as an outpatient. No further hypoglycemic episodes occurred. Discussion: Few cases report treatment of hypoglycemia in malignant insulinoma with octreotide. Octreotide has the dual effect of suppressing insulin secretion and tumor growth on insulinomas that express SSTR2 receptors. However, because somatostatin agonists also inhibit the secretion of glucagon, in insulinomas without SSTR2 expression, octreotide can aggravate hypoglycemia. This was especially a concern for our patient with a large tumor burden. Thus the short octreotide test was conducted. We suggest that the octreotide test of 100 mcg SQ octreotide injection followed by hourly measurements of glucose and insulin levels is a useful and convenient test to predict efficacy while monitoring for octreotide induced hypoglycemia. Finally the use of CGM in the outpatient setting enabled successful transition to octreotide LAR which improved the patient’s quality of life greatly by enabling once a month injections. Presentation: 6/3/2024