Endocrine Abstracts

Introduction: Hypoglycemia is a medical emergency that can have many different causes in etiology. Autoimmune hypoglycemia in patients with very high insulin levels should also be considered in the differential diagnosis.

Case: A 50-year-old man was admitted to our clinic for investigation and treatment of hypoglycemic episodes. He did not have any evidence for the use of oral antidiabetic medications, insulin, herbal substances. However, in our history, we learned that pregabalin and alfalipoic acid were given to the patient considering neuropathic pain and proton pump inhibitors for dyspeptic complains. Physical exam revealed a healthy-appearing middle-aged male with BMI of 21.4. Initial tests showed low venous blood glucose (44 mg/dl), high insulin levels >1000 μIU/ml, C-peptide 15.6 ng/ml. To rule out pancreatic or extrapancreatic insulinoma; abdominal ultrasound, abdominal computer tomography scan, abdominal MRI and Ga-68 DOTATATE PET/CT was performed. The results did not show an evidence of insulinoma. Intra-arterial calcium stimulation test was also performed to rule out insulinoma but the results were inconclusive. Anti-insulin antibody test was performed for the differential diagnosis and it was positive. The symptoms associated with low glucose levels and high serum insulin levels along with positive anti-insulin antibody lead us to the diagnosis of insulin autoimmune syndrome. According to the current literature suggesting the relationship between insulin autoimmune syndrome and alpha lipoic acid and proton pump inhibitors we discontinued that drugs and started alpha glucosidase treatment and nutritional management. During the follow up the patient did not report a hypoglisemic episode.

Conclusion: Insulin autoimmune hypoglycemia is a rare cause of endogenous hyperinsulinemic hypoglycemia. It is a condition that should be kept in mind in patients who have very high levels of insulin and who can not detect a specific focus through imaging modalities.