Hirata – Is Not a Peaceful Rice Paddy

Abstract

Background:
Insulin autoantibodies are an uncommon cause of non-diabetic hypoglycaemia in people who have never been exposed to insulin before. This condition is called Insulin Autoimmune Syndrome (IAS), or Hirata's Disease. Because of increased clinical awareness, instances are increasingly being found in various populations, although being more frequently reported in East Asian nations.
Case Presentation:
We describe two cases of middle-aged women, a 45-year-old homemaker and a 38-year-old nurse, who had low random blood glucose levels (35–59 mg/dL), giddiness, sweating, weariness, and tremors as symptoms of recurrent postprandial hypoglycaemia. Both received baseline blood tests and systemic checks that were normal. The results of the investigations showed significantly higher levels of C-peptide (1772 and 9782 pmol/L), insulin autoantibody titers (>100 and >200), and serum insulin (>1000 µU/mL). Both patients had a history of taking multivitamins that contained the known trigger alpha-lipoic acid. Hypoglycaemic episodes continued even after dietary changes and steroid treatment, although rituximab treatment produced long-lasting clinical improvement.
Discussion:
IAS is a rare but crucial differential diagnosis for hypoglycaemia that is not diabetic, particularly in individuals who are not receiving insulin therapy. It has been determined that alpha-lipoic acid frequently acts as a precipitating agent. Similar to findings in steroid-refractory cases reported by Batra et al., our patients showed conventional biochemical characteristics of IAS and reacted positively to rituximab, in accordance with earlier investigations. Prolonged morbidity and needless investigations can be avoided with early detection and awareness of IAS.
Conclusion:
Patients with increased insulin levels and spontaneous hypoglycaemia should be evaluated for IAS, especially if exogenous insulin is not being used. Effective care requires a high index of suspicion, triggering agent identification, and customized treatment, including immunosuppressive medication like rituximab.