Insulin autoantibody syndrome: Varying clinical presentations and response patterns of an underrecognized entity

Abstract

Context: Insulin autoantibody syndrome (IAAS) is considered to be a rare cause of hyperinsulinaemic hypoglycaemia. Lack of familiarity with the varied clinical manifestations leads to underdiagnosis. Localization techniques aimed at insulin-secreting neoplasms and nesidioblastosis, which are expensive often are ordered when the correct diagnosis is not made. Aims: We describe the myriad of clinical manifestations associated with IAAS based on single centre experience. Settings and Design: Retrospective analysis of patients who got admitted with symptoms suggestive of hypoglycaemia and underwent mixed meal test and prolonged hypoglycaemic test from 2016 to 2019. Subjects and Methods: Retrospective data of 12 patients with IAAS who were diagnosed in the threeyear time period between 2016 and 2019 are included in this analysis. Clinical details, biochemical parameters and imaging modalities were analysed. Statistical Analysis: All analyses were performed with SPSS software (version 17). Results: Total of twelve patients 12 (5 male and 7 females) were identified as IAAS. Median age of presentation was 57 years. Median insulin levels and median C-peptide levels were 300 miu/ml and 18.5 ng/ml respectively. Only 3 (25%) patients had spontaneous resolution. Steroid induced remission occurred by 3 months in the remaining patients. Intermittent hyperglycaemia was seen in 9 (75%) patients. Implicatable drug use preceding the occurrence of the clinical symptoms was observed in five patients. Conclusion: IAAS is not uncommon in India. The diagnosis should be pursued in patients with hyperinsulinaemic hypoglycaemia especially when insulin levels are very high or when there is intermittent hyperglycaemia.