GLUCOSE CHANGES IN A PATIENT WITH INSULIN AUTOIMMUNE SYNDROME AS MANIFESTED BY CONTINUOUS GLUCOSE MONITORING

ABSTRACT Objective: Insulin autoimmune syndrome (IAS) is an unusual cause of hypoglycemia in individuals without underlying diseases. Continuous glucose monitoring (CGM) has rarely been applied for IAS. We present a case of IAS with available 6-day CGM data. Methods: A 61-year-old Taiwanese man was admitted because of impaired consciousness while driving, caused by a low blood glucose level of 30 mg/dL. He regained consciousness fully after parenteral glucose administration. Results: During the prolonged fasting test, his C-peptide and insulin levels were respectively 11 ng/mL and 169.34 μIU/mL when plasma glucose was 41 mg/dL. Abdominal magnetic resonance imaging did not show any pancreatic abnormality. His 6-day CGM data revealed fasting hypoglycemia, several instances of postprandial hyperglycemia, and low blood glucose levels before lunch and dinner. Additional diagnostic findings included elevated anti-insulin antibody of 78.2%, thyrotoxicosis due to Graves disease, and gastric ulcer. He was discharg...