Insulin Autoimmune Syndrome: A Chinese Expert Consensus Statement

Insulin autoimmune syndrome (IAS) is a rare autoimmune disorder characterized by spontaneous hypoglycemia. The incidence of IAS is higher in East Asian populations compared to other populations. Delayed diagnosis and treatment can lead to recurrent hypoglycemia, significant glucose fluctuations, and adverse clinical outcomes, including life-threatening situations. Currently, no standardized guidelines exist for the diagnosis and treatment of IAS. This consensus aims to provide a systematic summary of the epidemiology, triggers, pathogenesis, clinical manifestations, diagnosis, differential diagnosis, treatment, and prognosis of IAS, with the objective of standardizing its clinical management.

Insulin Autoimmune Syndrome (Hirata Disease): A Comprehensive Review Fifty Years After Its First Description

Insulin autoimmune syndrome (IAS), also named Hirata's disease, is a rare condition characterized by hypoglycemic episodes due to the presence of high titers of insulin autoantibodies (IAA). IAS is a form of immune-mediated hypoglycemia, which develops when a triggering factor (ie, a medication or a viral infection) acts on an underlying predisposing genetic background. IAS pathogenesis involves the formation of insulin-IAA complexes that induce glycemic alterations with a double-phase mechanism: IAA prevent insulin to bind its receptor in the postprandial phase, possibly resulting in mild hyperglycemia; thereafter, insulin is released from the complexes irrespective of blood glucose concentrations, thus inducing hypoglycemia. The diagnosis of IAS is challenging, requiring a careful workup aimed at excluding other causes of hyperinsulinemic hypoglycemia. The gold standard for the definitive diagnosis is the finding of IAA in a blood sample. Because IAS is frequently a self-remitting disease, its management mostly consists of supportive measures, such as dietary modifications, aimed at preventing the development of hypoglycemia. Pharmacological therapies may occasionally be necessary for patients presenting with severe manifestations of IAS. Available therapies may include drugs that reduce pancreatic insulin secretion (somatostatin analogues and diazoxide, for instance) and immunosuppressive agents (glucocorticoids, azathioprine and rituximab). The purpose of this review is to provide a comprehensive analysis of the disease, by describing the burden of knowledge that has been obtained in the 50 years following its first description, took in 1970, and by highlighting the points that are still unclear in its pathogenesis and management.

The insulin autoimmune syndrome (IAS) as a cause of hypoglycaemia: an update on the pathophysiology, biochemical investigations and diagnosis

Insulin autoimmune syndrome (IAS) is considered to be very rare in Caucasians. Understanding its pathophysiology is paramount in (a) appreciating its potential impact on analyses of pancreatic hormones and (b) explaining its highly variable clinical manifestations in non-diabetic, non-acutely ill patients with indeterminate hypoglycaemia. The underlying aetiology of IAS is the presence of variable affinity/avidity endogenous insulin antibodies in significant amounts. The two types of insulin antibodies namely antibodies which bind insulin and/or proinsulin(s) and receptor antibodies (insulin mimetic) will be discussed. Their biochemical and immunological roles in causing hypoglycaemia will be highlighted. Clinical manifestations of IAS can vary from mild and transient to spontaneous, severe and protracted hypoglycaemia necessitating in extreme cases plasmapheresis for glycaemic control. Antibodies of IAS can interfere in pancreatic immunoassay tests causing erroneous and potentially misleading results. Thorough testing for endogenous insulin antibodies must be considered in the investigations of non-diabetic, non-acutely ill patients with indeterminate and/or unexplained hypoglycaemia.

Hydrothermally modified slow release corn starch: a potential new therapeutic option for treating hypoglycemia in autoimmune hypoglycemia (Hirata's disease)

We report the successful treatment of autoimmune hypoglycemia in an 82-year-old non-diabetic Caucasian male with hydrothermally modified slow release corn starch, a product which is used in other conditions associated with hypoglycemia, most typically glycogen storage disease type I. An 82-year-old-Caucasian male presented with recurrent spontaneous hypoglycemia as low as 30 mg/dl following in-patient treatment for community acquired pneumonia. During a fasting-test, symptomatic hypoglycemia occurred. Plasma concentrations of c-peptide and insulin were considerably elevated. Autoimmune hypoglycemia was confirmed by the presence of insulin autoantibodies. While dietary restriction alone did not result in sufficient glucose control in this patient with autoimmune hypoglycemia, treatment with hydrothermally modified slow release corn starch led to stable euglycemia. This easy, well tolerated and non-invasive treatment may constitute a new therapeutic option for hypoglycemia in patients with autoimmune hypoglycemia who do not achieve sufficient control of hypoglycemia by dietary restriction alone.

Autoimmune forms of hypoglycemia

Autoimmune syndromes are a rare cause of hypoglycemia characterized by elevated levels of insulin in the presence of either anti-insulin antibodies (insulin autoimmune syndrome) or anti-insulin receptor antibodies (type B insulin resistance). Insulin autoimmune syndrome is the third leading cause of hypoglycemia in Japan, but has rarely been described in the non-Asian population.In the current study, we report the clinical and biochemical characteristics and clinical course of 2 white patients with insulin autoimmune syndrome, and present a literature review of non-Asian patients reported with insulin autoimmune syndrome. Also, we describe the clinical and biochemical characteristics of patients reported in the literature with type B insulin resistance who manifested hypoglycemia. We compare the clinical and laboratory features of insulin autoimmune syndrome and type B insulin resistance with each other and with other forms of hyperinsulinemic hypoglycemia.Autoimmune forms of hypoglycemia are uncommon. However, they should be considered in any patient with hypoglycemia in the setting of unsuppressed insulin levels associated with anti-insulin or anti-insulin receptor antibodies. Making the correct diagnosis may spare a hypoglycemic patient from an unnecessary pancreatic surgical procedure.