SHM Converge Scientific Abstract ePoster Gallery-Blue Moon in a Village Square: Insulin Autoimmune Syndrome

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This case report describes a 74-year-old man with recurrent symptomatic hypoglycemia caused by insulin autoimmune syndrome (IAS), a rare autoimmune disorder also known as Hirata’s disease. IAS occurs when insulin autoantibodies bind endogenous insulin, leading to fluctuating insulin availability and episodes of hypoglycemia, often without prior insulin use or pancreatic disease.<br /><br />The patient had a history of hemochromatosis, hypertension, atrial fibrillation, and hyperlipidemia, and was taking amiodarone and berberine. He presented to the emergency department three times in one week with nausea, syncope, diaphoresis, and blood glucose of 48 mg/dL, with only temporary improvement after D50 administration. He remained pale and diaphoretic but was otherwise neurologically improved after glucose treatment.<br /><br />Initial evaluation showed normal liver function, HbA1c of 4.8%, negative drug screen, undetectable sulfonylurea levels, and normal cortisol. During a hypoglycemic episode, insulin and proinsulin levels were markedly elevated, and insulin autoantibodies were extremely high. CT, MRI, and PET imaging were unrevealing, helping exclude insulinoma or other structural causes.<br /><br />He continued to have recurrent glucose readings in the 40s despite continuous dextrose infusion, octreotide, and a consistent carbohydrate diet. Endocrinology was consulted. After starting prednisone 40 mg daily, his hypoglycemic episodes improved significantly and eventually resolved.<br /><br />The case highlights that IAS is extremely rare, can be associated with autoimmune disease or certain medications/supplements, and is frequently misdiagnosed as insulinoma, leading to unnecessary invasive workups or surgery. A high index of suspicion is essential, especially when hypoglycemia occurs with very high insulin and insulin antibody levels.

Asset Subtitle

Muftah Mahmud

Meta Tag

Author List Juan Vargas, Muftah Mahmud, Neychelle Rocca

Category Clinical Vignettes

Concept Insulin Autoimmune Syndrome

Concept Insulin Autoantibodies

Concept Endogenous Hyperinsulinemic Hypoglycemia

Concept Insulinoma

Concept Insulin Level

Distinguished Non-Finalist

Presenter Organization Midwestern University Internal Medicine Residency Program,Verde Valley Medical Center

Presenting Author Muftah Mahmud

Track Adult

Keywords

insulin autoimmune syndrome

Hirata disease

recurrent hypoglycemia

insulin autoantibodies

hyperinsulinemia

prednisone treatment

insulinoma differential

autoimmune disorder

amiodarone

berberine

Insulin Autoimmune Syndrome

Insulin Autoantibodies

Endogenous Hyperinsulinemic Hypoglycemia

Insulinoma

Insulin Level