Endocrine Abstracts

Introduction: Insulinoma is a rare, generally benign neuroendocrine tumor, primarily manifesting as hypoglycemia in non-diabetic patients. Although surgery is the gold standard treatment for insulinoma, managing hypoglycemia becomes challenging in cases where surgery is not feasible. This challenge arises due to significant side effects that often limit the use of most drugs and therapeutic alternatives.

Case report: A 90-year-old non-diabetic man was admitted to our hospital for study due to unexplained recurrent symptomatic hypoglycemia. After excluding common causes of outpatient hypoglycemia, a post-fasting blood test revealed endogenous hyperinsulinism with blood glucose at 2.4 mmol/l, insulin at 9.6 μIU/ml (66.6 pmol/l, elevated), proinsulin at 14.6 pmol/l (elevated), and C-peptide at 2.31 ng/ml (0.76 nmol/l, elevated). Anti-insulin antibodies were negative, and urinary sulfonylurea determination was also negative. An abdominal CT scan identified a 15-mm solid nodular lesion in the tail of the pancreas. A gallium-68-tetraxetane Tyr3-octreotate PET-CT scan indicated that the mass had a maximum normalized uptake value of 19.22 and expressed somatostatin receptors 2 and 5, confirming the diagnosis of insulinoma. Due to the patient’s high surgical risk, conservative medical management was chosen. Upon admission, intravenous dextrose treatment was initiated. After confirming the suspicion of insulinoma, low doses of diazoxide were attempted. However, due to the development of symptoms such as heart failure, lower limb edema, and hyponatremia upon increasing the diazoxide dose, a dietary approach took priority. The use of modified corn starch in fractionated doses, guided by continuous glucose monitoring, was introduced.

Discussion: There is limited evidence supporting the use of glycosade to treat hypoglycemia in insulinoma. Glycosade, a modified corn starch with slower absorption than normal corn starch, is employed in patients with glycogenosis to prolong the time between meals. Given its absorption profile, ease of administration, minimal short-term side effects, and relatively low cost, we consider it a valuable dietary alternative for controlling hypoglycemia. This is especially relevant today, as continuous glucose monitoring allows for a more accurate estimation of each patient’s hypoglycemia pattern. This approach proves particularly applicable in patients who are inoperable, frail, and at high risk of adverse effects from traditional medical therapies.