Endocrine Abstracts

Introduction: Insulin autoimmune syndrome (IAS) is characterized by spontaneous hypoglycemia caused by insulin autoantibodies (IA) in the absence of exogenous insulin administration. The occurrence of IAS may be influenced by a genetic predisposition determined by HLA class II. IAS is frequently reported in Japanese and Koreans due to their genetic predisposition (HLA-DRB1*0406) rather than in the Caucasians. Some drugs containing sulfhydryl compounds are known to initiate the onset of IAS. A-lipoic acid (ALA) contains two sulfur atoms and can promote insulin S-S bounding dissociation and expose insulin to the antigen presenting cells. T cells of predisposed patients are stimulated, resulting in IA formation.

Case description: A 52-year-old female with medical history of oral medical supplements consumption, containing ALA, was admitted at the emergency Department with severe hypoglycemia accompanied by neuroglycopenic and adrenergic symptoms. Intravenous dextrose solutions along with many short mixed meals were administrated. After the exclusion of adrenal insufficiency and hypothyroidism, a 72-hour fasting test was attempted, but was ended 3 hours later because the patient experienced palpitation and sweating with low blood glucose level (39 mg/dl). Serum insulin and c-peptide levels were high (27.7 µI U/ml and 2.7 ng/ml respectively). Pancreatic Magnetic tomography and endoscopic ultrasonography did not prove the existence of an insulinoma while IA levels were very high (101 U/ml). The excessive consumption of medical supplements, containing ALA [which improve glucose metabolism], the absence of other clinical signs and the high IA levels established the diagnosis of IAS. ALA supplementations were discontinued and diazoxide was initiated. Glucose levels were increased and after three months of treatment, the patient was recovered completely. IA were decreased, but they have not been normalized yet. Diazoxide treatment was gradually decreased and discontinued. Her HLA genotype analysis has not been completed yet.

Conclusion: IAS should be considered in patients with sudden episodes of hypoglycemia, when the imaging investigation was unremarkable and medications containing sulfhydryl compounds, such as ALA were consumed.

References

1. Redmon JB, et al. Endocrinol Metab Clin North Am. 1999 28(3) 603–618.

2. Bresciani E, et al. Diabetes Care 2011 34.