ODP157 A Case of Pancreatic Insulinoma With Hypoglycemia Unawareneness

CLINICAL CASE: An 84-year-old woman with hypertension, type 2 diabetes, and a history of frequent falls, presented to the hospital after one week of recurrent falls with progressive worsening right-sided weakness, speech difficulties, and urinary incontinence. She was found to have a 2.8cm subacute subdural hematoma with midline shift and underwent successful subdural evacuation placement, nevertheless, her course was complicated by asymptomatic hypoglycemia. During her prolonged hospitalization, she experienced a 15-pound weight loss, initially attributed to poor oral intake. She was previously on glimepiride for her diabetes but this was discontinued about two months prior for low sugars. The patient did not meet Whipple's triad, as she denied symptoms of hypoglycemia and felt no different once her glucoses normalized. However, nursing staff noticed a slight difference in her cognition and behavior during these hypoglycemic episodes, which improved after correction. Laboratory testing: A fasting protocol was initiated. After seven hours, her finger stick blood glucose dropped to 42 mg/dL. Her Insulin 23.8 uU/mL (1.9-23), Proinsulin 46.9 pmol/L (<10), and C-peptide 5.3 ng/mL (0.9-7.1) were relatively high at this time, despite a confirmed low plasma glucose of 47 mg/dL. Beta-hydroxybutyrate was 0.24 mmol/L (<0.3) with Hemoglobin 16.5 G/dL (11.7-15),and HbA1c 5.6%. Her blood glucoseimproved to 126 mg/dL after administration of 1mg glucagon. Anti-Insulin antibody <5 uU/mL and a sulfonylurea screen were negative. The fasting protocol was discontinued and she was started on Dextrose 10% infusion, then transitioned to diazoxide. A dedicated MRI of the abdomen did not demonstrate any pancreatic lesions. An esophagogastroduodenoscopy was then performed, revealing a 12-mm mass in the head/uncinate of the pancreatic body. FNA confirmeda low-grade, well-differentiated neuroendocrine tumor. Immunohistochemical stains were positive for Insulin and Synaptophysin, and negative for Chromogranin, supporting the diagnosis of insulinoma. Endoscopic ultrasound with successful ethanol ablation was completed. Subsequently, her hypoglycemia rapidly improved off treatment. CONCLUSION: Per the 2009 Endocrine Society guidelines, evaluation of recurrent low blood sugar is only recommended if Whipple's triad is present. However, this case highlights that hypoglycemia unawareness can mask Whipple's triad. It is not unusual for patients with longstanding hypoglycemia to lose neurogenic and neuroglycopenic symptoms. This can complicate and delay the diagnosis of insulinoma, as it did in this patient with multiple falls. Her documented weight loss, decreased oral intake, and relatively high HbA1c are not classic of insulinoma and were further obstacles for diagnosis. Endocrine guidelines should incorporate the importance of hypoglycemia unawareness into its algorithm. In this setting, we should consider a lower threshold to initiate fasting protocol and biochemical testing during a hypoglycemic event (<55mg/dL). Presentation: No date and time listed