SUN-070 - Challenges of Insulinoma Management in Pregnancy: Role of Cornstarch and Continuous Glucose Monitoring

Introduction:
Insulinoma is a rare insulin-producing neuroendocrine tumor that causes recurrent hypoglycemia. Diagnosis and management during pregnancy are challenging and rarely reported, as definitive imaging and surgical intervention are contraindicated. Severe hypoglycemia poses maternal and fetal risk, and standard medical therapy such as diazoxide has limited safety data. Here, we present a case of insulinoma managed during pregnancy using uncooked cornstarch guided by continuous glucose monitoring.

Case:
A 39-year-old Hispanic female initially presented with recurrent episodes of loss of consciousness. Laboratory results showed glucose of 46 mg/dl ( 70-111 mg/dl), C-peptide 1.64 ng/dl (0.80 - 6.90 ng/ml), free insulin of 288 uU/mL (0-17 uU/mL), A1c of 3.7% (3.9 - 6.9 %), and elevated insulin antibodies. She denied classic hypoglycemia symptoms such as weakness, dizziness, tremors, or use of sulfonylureas, insulin, or GLP-1 receptor agonists. Further outpatient evaluation redemonstrated hypoglycemia with inappropriately normal/high insulin, C-peptide and proinsulin. ACTH, morning cortisol and thyroid function were normal. These findings were consistent with endogenous insulin-mediated hypoglycemia. CT image noted a 1.7-cm pancreatic head lesion concerning for an insulinoma. At that time, pregnancy was identified, so PET-DOTATATE localization and surgical resection were deferred until postpartum. Continuous glucose monitoring (CGM) was initiated with initial data showing hypoglycemia with 27% of glucose values low (54-70 mg/dl) and 10% very low (less than 54 mg/dL), predominantly nocturnal, with hypoglycemia unawareness. At 23–24 weeks’ gestation, she was started on a low–glycemic index diet and 5-6 tablespoons of uncooked cornstarch at bedtime to provide sustained glucose release. CGM data guided further diet changes, including cornstarch dosing and avoidance of simple carbohydrates. By 26–28 weeks’ gestation, CGM data showed improved hypoglycemia, with low glucose time reduced to 15% and very low to 2%, reaching < 1% low glucose by 34 weeks. At 36 weeks, mild hypoglycemia recurred when nausea limited cornstarch intake. She delivered a healthy infant at 39 weeks (birth weight 2610 g) via uncomplicated vaginal delivery, without maternal or neonatal hypoglycemia.

Conclusion:
Pregnancy significantly limits the diagnostic and treatment options for patients with insulinoma. First-line therapies such as diazoxide, somatostatin analogs, and surgical resection are contraindicated and not well studied. This case highlights that CGM-guided titration of cornstarch and low-glycemic-index diet can effectively limit hypoglycemia in pregnancy. Combined with the increased physiologic insulin resistance during the last trimester, this strategy allowed the patient to safely reach term delivery, and definitive tumor treatment could be addressed postpartum.

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