Abstract Introduction Insulin Autoimmune Syndrome (IAS), also known as Hirata's disease, is a rare cause of endogenous hyperinsulinemic hypoglycemia characterized by the presence of insulin autoantibodies in individuals who have not received exogenous insulin. Chronic corticosteroid therapy can suppress the hypothalamic-pituitary-adrenal axis, potentially leading to secondary adrenal insufficiency upon abrupt discontinuation. We present a case with RA who presented with hypoglycemia after the discontinuation of long-term corticosteroid therapy. This presentation initially raised suspicion of adrenal insufficiency, but the underlying cause was ultimately identified as Hirata's disease. Clinical Case A 63-year-old male with a history of RA and coronary artery disease presented to the emergency department with recurrent syncopal attacks due to severe hypoglycemia. On physical examination, the patient was confused and tachycardic. His blood glucose level was 36 mg/dL, and he was started on a dextrose infusion. The patient had a similar presentation with hypoglycemia and syncope approximately 10 days earlier. A history revealed that he had recently and abruptly discontinued his long-term prednisone therapy. Due to the suspicion of secondary adrenal insufficiency, he was administered intravenous methylprednisolone and admitted to the ward. Upon admission, the patient experienced another episode of hypoglycemia. To investigate the cause, blood tests for adrenal insufficiency and other potential etiologies of hypoglycemia were ordered. The laboratory results from the hypoglycemic episode are shown in Table 1. The cortisol level was 12 µg/dL, which was not consistent with primary adrenal insufficiency. Elevated insulin and C-peptide levels were consistent with hyperinsulinemic hypoglycemia. The insulin level of 1000 mlU/L strongly suggested autoimmune hypoglycemia, and anti-insulin antibody (IAs) levels were ordered. The IAs level was positive (123 U/mL), leading to the diagnosis of Hirata's disease. The abdominal CT scan showed no pancreatic pathology. The patient was started on acarbose and his blood sugar was monitored. Since his hypoglycemic episodes persisted, prednisolone was added to the treatment regimen, after which no further hypoglycemia was observed. His IAs levels subsequently decreased to 57.6 U/mL and then to 14 U/mL, and the prednisolone was gradually tapered and discontinued. The patient was followed up while continuing acarbose, and no further hypoglycemic episodes occurred. Conclusion This case report describes how chronic corticosteroid therapy can mask Insulin Autoimmune Syndrome (IAS), a condition where high-titer insulin autoantibodies cause postprandial hypoglycemia. Treatment focuses on preventing low blood sugar and suppressing the immune response. It is crucial for clinicians to consider IAS in the differential diagnosis of unexplained hypoglycemia, particularly in patients with autoimmune diseases or those on immunomodulatory drugs.Table 1:Laboratory values of the patient
Yağcı et al. (Thu,) studied this question.