P-23 Insulin autoimmune syndrome possibly induced by Alpha-Lipoic acid

Abstract

Abstract Introduction Insulin autoimmune syndrome (IAS) is a relative rare cause of hypoglycemia due to the presence of extremely high circulating insulin levels and elevated serum concentrations of autoantibodies to human insulin despite no prior exposure to exogenous insulin, insulin analogues or oral hypoglycemic agents. It is characterized by repeated fasting hypoglycemia or episodes of hypoglycemia late after meals in non-diabetic, non-acutely ill patients. Increasing the titer of insulin autoantibodies and immune reactive insulin occurs owing to both genetic influences and environmental triggers such as medication, genetic instability and other factors. It is associated with the use of drugs comprising sulfhydryl groups, such as methimazole, clopidogrel and alpha lipoic acid, mostly. Insulin autoantibodies appear a few weeks after the exposure of sulfhydryl radicals. Here, we summarize the case of IAS caused by drug administration. Clinical Case A 60-year-old female patient who has a history of migraine for 30 years was referred to our hospital for feeling of hunger, dizziness, sweating, tremor, and palpitations for 1 month. These symptoms had commenced episodically, soon after starting 600 mg/day of alpha lipoic acid. She was diagnosed with hypoglycemia based on a plasma glucose concentration of 31 mg/dL. There was no personal or family history of diabetes mellitus, or previous use of oral hypoglycemic drugs such as sulfonylureas or exogenous insulin. No abnormality was detected in the systemic examination. She had no smoking and alcohol abuse. Her regular medication was tricyclic antidepressant (amitriptyline). Laboratory results are presented in Table 1. On our evalution, the serum levels of insulin, C-peptide, and anti-insulin antibody titers were inappropriately elevated in the presence of hypoglycemia, confirming the diagnosis of hyperinsulinemic hypoglycemia. Thyroid function, human growth hormone, insulin growth factor-1 (IGF-1), and cortisol result were within normal limits. Screening for antinuclear factor, serum protein electrophoresis, serology for viral hepatitis, and other autoimmune diseases were negative. Insulinoma was excluded with computed tomography. In light of the above results, a diagnosis of IAS was made with possible alpha lipoic acid. Because, alpha lipoic acid was the only medication being taken associated with a sulfhydryl group. The patient was prescribed oral methylprednisolone (32 mg once daily), alpha lipoic acid was withdrawn. Hypoglycemia did not occur after methylprednisolone treatment of follow-up. Methylprednisolone treatment was tapered to 4 mg once daily within 2 months. The insulin, and anti-insulin antibody titers had decreased. Conclusion We report a rare case of IAS. Sulfhydryl group containing drugs such as alpha lipoic acid might induce or exacerbate hypoglycemia in patients with a history of IAS. For this reason, the use of alpha lipoic acid should be questioned in patients with IAS. Table 1. Laboratory test results