Autoimmune forms of hypoglycemia

A clinical case of insulin autoimmune syndrome with monoclonal gammopathy of uncertain significance; complexity in management

Insulin autoimmune syndrome (IAS) is a rare cause of spontaneous hypoglycaemia. We discuss a 91-year-old Caucasian lady who presented with syncope and episodic adrenergic and neuroglycopenic symptoms. Despite significantly elevated insulin, C-peptide, and proinsulin levels with the presence of anti-insulin antibodies, a pancreatic mass was not identified. Serum immunoelectrophoresis demonstrated monoclonal gammopathy of undetermined significance (MGUS). Treatment involved high-dose steroids, diazoxide, corn starch and acarbose, however the patient passed away four months later due to worsening co-morbidities. The management of IAS in the setting of MGUS is challenging.

Spontaneous Hypoglycaemia due to Insulin Autoimmune Syndrome in Six Cases, Response to Steroid Therapy and Rituximab

Introduction

Dr. Hirata of Japan first described insulin autoimmune syndrome (IAS) in 1970. Seven hundred ninety-five cases of this rare syndrome have been reported from Japan and China and 29 from India. IAS has the following characteristic features 1) severe spontaneous attacks of hyperinsulinemic hypoglycaemia, 2) high total immunoreactive insulin levels, 3) elevated insulin autoantibody (IAA) titres, 4) no prior exposure to exogenous insulin, and 5) no pathological abnormalities of the pancreatic islet cells.

Methods

We treated six cases of IAS with high doses of prednisolone for 4-6 weeks and then gradually reduced the doses. Diagnosis of IAS was established by documenting Whipple's triad of symptoms and signs of hypoglycaemia, blood sugar <55 mg/dl, improvement of symptoms with dextrose infusion, inappropriately increased insulin levels >3 uU/ml, C-peptide levels >0.6 ng/ml, and increased titres of anti-insulin autoantibodies. Insulinoma and non-pancreatic tumours were ruled out by CECT (contrast-enhanced computerised tomography) or MRI (magnetic resonance imaging) of the abdomen and if necessary endoscopic ultrasonography and gallium 68 Dotanoc PET (positron enhanced tomography). Autoimmune screening and serum electrophoresis were done to rule out multiple myeloma. Monitoring of the patient's blood sugars was done by the laboratory, glucometer readings, and a freestyle libre glucose monitoring system.

Results

Remission of hypoglycaemic episodes, hyperglycaemic episodes, and marked reduction of serum insulin and insulin autoantibodies in four out of six patients with diet therapy and steroids. Two patients resistant to steroids were treated with rituximab successfully. Patient 6 developed serious complications of cytomegalovirus and Pneumocystis carnii after rituximab, which were treated successfully.

Conclusion

A careful history including recent infections, medications, and vaccinations provides vital clues in the evaluation. An increased awareness of IAS will prevent unnecessary and costly investigations and surgery. Although it is often self-remitting, steroids are contributory in severe cases. Immunosuppressives are used successfully in cases refractory to steroids. Continuous glucose monitoring system (CGMS), by freestyle libre glucose monitoring system, provided real-time blood sugar values, total time in hypoglycaemia, and total time in the range (TIR), which proved very valuable in managing IAS patients. Low CGMS values should be corroborated clinically and with laboratory or glucometer values.

Systematic Review-Type B Insulin Resistance With Isolated Hypoglycemia and Suppressed Insulin

OBJECTIVE

Type B insulin resistance syndrome is a rare autoimmune disorder affecting glucose homeostasis, characterized by serum autoantibodies to the insulin receptor (AIRAbs). Patients typically present with severe insulin resistance. A mixed hyper- and hypoglycemia phenotype may also occur, as may isolated hypoglycemia. The classic biochemical pattern comprises elevated insulin levels despite hypoglycemia; however, a small proportion of cases demonstrate "isolated hypoglycemia with low insulin." The primary objectives of this systematic review were to identify the clinical characteristics and outcome of this subgroup.

DESIGN

Systematic review of cases with hypoglycemia with suppressed insulin. Exclusions: hyperglycemia, elevated insulin, AIRAbs not confirmed.

METHODS

PubMed, Medline, and Embase databases were searched up until February 2023 and complemented by manual citation search. The Joanna Briggs Institute critical appraisal checklist for case reports was used to assess bias.

RESULTS

A total of 5342 articles were identified after duplicate removal. Eleven, all case reports, met all inclusion criteria and were included. Cases belonging to this subgroup were more diverse in sex, age, and ethnicity when compared with type B insulin resistance as a whole. Of the 11 cases, 3 developed lymphoma. High-dose corticosteroid therapy appeared to be effective therapy for the hypoglycemia, with often rapid response.

CONCLUSIONS

Isolated hypoglycemia with low insulin forms a rare subgroup of type B insulin resistance. These patients lack the common characteristics of hyperinsulinemic hypoglycemia and hyperglycemia/insulin resistance. Furthermore, while coexisting autoimmune disease is commonly observed, there is potentially an association with aggressive lymphoma, the onset of which may be delayed.

Recurrent hypoglycemia induced by clopidogrel: A case report and mini review

This report describes a patient who developed recurrent hypoglycemia episodes after 23 days of antiplatelet therapy with clopidogrel for left subclavian artery stent implantation. The patient suffered from palpitation, profuse sweating and weakness on the 23rd day of clopidogrel treatment. The minimum plasma glucose was 2.2 mmol/L, and the hypoglycemia was associated with significantly elevated levels of insulin. A diagnosis of insulin autoimmune syndrome (IAS) was made with the presence of insulin autoantibody and a comprehensive differential diagnosis of other conditions related with hypoglycemia. Clopidogrel was stopped, and the patient was treated with acarbose and had frequent low-carbohydrate meals; his hypoglycemia did not occur within 10 days. To date, seven cases of IAS induced by clopidogrel have been reported. Most reported cases were male aged in their 70s, and the hypoglycemic attack appeared 1-4 weeks after exposure to clopidogrel, characterized by severe hyperinsulinemia hypoglycemia with high titers of insulin autoantibodies. Most IAS cases can resolve spontaneously when they stop using the trigger medicine. Severe cases had been treated with drugs that reduce pancreatic insulin secretion (such as somatostatin and diazoxide), immunosuppressants (glucocorticoids, azathioprine and rituximab) and even immunoadsorption to remove the insulin autoantibody from the body. Considering the hypoglycemic attack might increase the risk of cardiovascular events among patients taking clopidogrel, we recommend that doctors should be aware of IAS as a rare severe adverse effect of clopidogrel, and be vigilant for the symptoms related with hypoglycemia in clopidogrel users.

Clinical Features and Outcome Analysis of Type B Insulin Resistance Syndrome: A Single-Center Study in China

CONTEXT

Type B insulin resistance syndrome (TBIRS) is a rare condition, for which effective treatment remains challenging.

OBJECTIVE

This work aimed to summarize the clinical characteristics of TBIRS and explore effective therapeutic strategies.

METHODS

The clinical manifestations, biochemical indices, and treatment of 8 patients (3 men and 5 women) with TBIRS from Peking Union Medical College Hospital were retrospectively analyzed and their clinical outcomes were evaluated.

RESULTS

The average age of the patients was 49.5 ± 16.5 years, and the duration of the disease ranged from 2 months to 1 year. Seven patients with hyperglycemia had normal/lower triglycerides (TGs) and lower insulin-like growth factor 1 (IGF-1) levels. One patient complained of intractable hypoglycemia. Five patients had accompanied systemic lupus erythematosus, 2 had mixed connective tissue disease, and 1 had undifferentiated connective tissue disease. Five patients had acanthosis nigricans and 3 women of child-bearing age had hyperandrogenism. All 8 patients were treated with glucocorticoids combined with immunosuppressants, among whom, 5 received high-dose glucocorticoid pulse therapy followed by conventional-dose glucocorticoid therapy, all of whom achieved partial remission within 2 to 4 weeks. Among the 3 patients receiving conventional glucocorticoid therapy, 2 achieved partial remission within 2 to 4 weeks. Six patients were tracked for 10 weeks to 4 years; 4 and 2 achieved complete and partial remission, respectively.

CONCLUSION

Decreased serum complement 3 and IGF-1 levels and normal/decreased TG levels act as striking biochemical features of TBIRS. High-dose glucocorticoid pulse therapy followed by conventional-dose long-term therapy combined with immunosuppressants achieves good clinical efficacy.

Investigation and Causes of Spontaneous (Non-Diabetic) Hypoglycaemia in Adults: Pitfalls to Avoid

Although adult spontaneous (non-diabetic) hypoglycaemia is rare, its recognition is important for the preventative or curative treatment of the underlying cause. Establishing Whipple's triad-low blood glucose, neuroglycopaenia and resolution of neuroglycopaenia on increasing blood glucose levels to normal or above-is essential to verify hypoglycaemia. Awareness that hypoglycaemia may occur in severely ill patients is important for its prevention. Further investigation in such cases is unnecessary unless another cause of hypoglycaemia is suspected. Patients are often asymptomatic and normoglycaemic at review. Their history of medication, self-medication, access to hypoglycaemic drugs, alcohol use and comorbidity may provide aetiological clues. The investigation involves obtaining blood samples during symptoms for laboratory glucose measurement or provoking fasting or postprandial hypoglycaemia as directed by symptoms. If confirmed, insulin, c-peptide, proinsulin and beta-hydroxybutyrate are analysed in hypoglycaemic samples. These will classify hypoglycaemia due to non-ketotic hyperinsulinaemia, non-ketotic hypoinsulinaemia and ketotic hypoinsulinaemia, and direct investigations to identify the underlying cause. There are, however, many pitfalls that may mislabel healthy individuals as "hypoglycaemic" or misdiagnose treatable or preventable causes of spontaneous hypoglycaemia. Clinical acumen and appropriate investigations will mostly identify hypoglycaemia and its cause.

A rare case of autoimmune dysglycemia syndrome associated with systemic lupus erythematosus and dermatomyositis

Autoimmune dysglycemia syndrome (ADS) is a rare condition that presents as episodes of hypoglycemia as well as hyperglycemia and is classified as insulin autoimmune syndrome (IAS) and type B insulin resistance (TBIR). Autoimmunity plays a key role in the pathogenesis of this disorder, as evidenced by the presence of autoantibodies against endogenous insulin or the insulin receptor, and by its association with rheumatologic disorders. Treatment usually includes glycemic control and immunomodulatory agents. We report a case of a 31-year-old woman who was admitted for severe hypoglycemia. Further workup revealed underlying systemic lupus erythematosus (SLE) with renal involvement. During hospitalization, she continued to experience episodes of fasting hypoglycemia, as well as episodes of postprandial hyperglycemia. Hypoglycemia associated with a high serum insulin concentration and positive anti-insulin antibodies were consistent with IAS. Likewise, hyperglycemia and hypoglycemia in association with weight loss, acanthosis nigricans, polycystic ovarian syndrome, and normotriglyceridemia strongly suggested TBIR, although testing for antibodies against the insulin receptor was not available in Peru. Immunosuppressive therapy and metformin were indicated, resulting in remission of SLE and ADS. Years later, the patient exhibited features of dermatomyositis, such as Raynaud’s phenomenon, muscular weakness, heliotrope exanthema, and elevated muscle enzymes. Once again, the patient received immunosuppressive therapy. ADS is an infrequent cause of hypoglycemia, and the coexistence of its two pathophysiological mechanisms in a patient with SLE and subsequent development of dermatomyositis is even more rare. Our case is the first one reported describing this association.

A rare case of autoimmune dysglycemia syndrome associated with systemic lupus erythematosus and dermatomyositis

Autoimmune dysglycemia syndrome (ADS) is a rare condition that presents as episodes of hypoglycemia as well as hyperglycemia and is classified as insulin autoimmune syndrome (IAS) and type B insulin resistance (TBIR). Autoimmunity plays a key role in the pathogenesis of this disorder, as evidenced by the presence of autoantibodies against endogenous insulin or the insulin receptor, and by its association with rheumatologic disorders. Treatment usually includes glycemic control and immunomodulatory agents. We report a case of a 31-year-old woman who was admitted for severe hypoglycemia. Further workup revealed underlying systemic lupus erythematosus (SLE) with renal involvement. During hospitalization, she continued to experience episodes of fasting hypoglycemia, as well as episodes of postprandial hyperglycemia. Hypoglycemia associated with a high serum insulin concentration and positive anti-insulin antibodies were consistent with IAS. Likewise, hyperglycemia and hypoglycemia in association with weight loss, acanthosis nigricans, polycystic ovarian syndrome, and normotriglyceridemia strongly suggested TBIR, although testing for antibodies against the insulin receptor was not available in Peru. Immunosuppressive therapy and metformin were indicated, resulting in remission of SLE and ADS. Years later, the patient exhibited features of dermatomyositis, such as Raynaud’s phenomenon, muscular weakness, heliotrope exanthema, and elevated muscle enzymes. Once again, the patient received immunosuppressive therapy. ADS is an infrequent cause of hypoglycemia, and the coexistence of its two pathophysiological mechanisms in a patient with SLE and subsequent development of dermatomyositis is even more rare. Our case is the first one reported describing this association.

Type B Insulin Resistance Syndrome: A Rare Cause of Hypoglycemia

We describe a case of a Black female patient with a history of type 2 diabetes mellitus and systemic lupus erythematosus, who had a subacute onset of severe hypoglycemia that persisted after cessation of insulin therapy. Biochemical testing revealed hyperinsulinemic hypoglycemia, normal serum triglycerides, and high-normal serum adiponectin levels. Abdominal imaging demonstrated an 11-mm cystic pancreatic lesion. Her clinical history and biochemical test results raised suspicion for type B insulin resistance syndrome (TBIRS), which was confirmed on anti-insulin receptor antibody testing. The patient's hypoglycemia was managed with dietary modification therapy and continuous glucose monitoring. The severity and frequency of hypoglycemic episodes decreased spontaneously. We describe TBIRS and its uncommon hypoglycemic presentation, analyze factors that put TBIRS among the differential diagnosis, and discuss the treatment of TBIRS-associated hypoglycemia.

Clopidogrel as a Distinctive Cause of Insulin Autoimmune Syndrome: A Systematic Case Review

The sulfhydryl group of clopidogrel metabolite could induce insulin autoimmune syndrome (IAS) with hypoglycemia as the major symptom. For patients with cardiovascular disease taking clopidogrel for vascular protection, this adverse event hypoglycemia increases the risk of cardiovascular events. However, discontinuing clopidogrel leaves patients without appropriate antiplatelet therapy. Treating IAS with glucocorticoids is also risky for these patients' primary cardiovascular diseases. Early recognition and appropriate treatment of clopidogrel-induced IAS (CIAS) would be beneficial for patients. This research aimed to discover the clinical features and investigate optimal therapeutic management of CIAS. We systematically searched for cases of CIAS in PubMed and Embase and performed data mining in Food and Drug Administration Adverse Event Reporting System (FAERS). In the CIAS series, clinical features were summarized and compared to 287 IAS cases, including demographic information, HLA alleles, onset, and symptoms. The therapeutic effect of glucocorticoids was compared between the receiving group and the not-receiving group. The possibilities of common antiplatelet drugs to induce hypoglycemia/IAS were investigated with chemical structure and FAERS reports. A CIAS series of 51 patients was established. CIAS had an onset age of 74.8±8.6 years old, 92.2% male, and a balanced proportion of East Asians and non-East Asians. Confusion occurred more frequently in CIAS than in IAS from various causes, while the other symptoms and hypoglycemia types were similar. The recovery time was approximately the same whether using glucocorticoids/immunotherapy in CIAS or not. Among common antiplatelet drugs, ticagrelor and rivaroxaban were unlikely to induce hypoglycemia/IAS. Clopidogrel is a distinctive cause of IAS featuring an elderly male presenting confusion as the symptom of hypoglycemia. Glucocorticoids/immunotherapy might not be necessary for the long-term recovery of CIAS. To balance the risks of hypoglycemia and cardiovascular events, substituting clopidogrel with ticagrelor and rivaroxaban might be considered.

A Novel In Vitro Assay Correlates Insulin Receptor Autoantibodies With Fasting Insulin in Type B Insulin Resistance

CONTEXT

Severe insulin resistance (IR) in the presence of insulin receptor autoantibodies (InsR-aAb) is known as type B insulin resistance (TBIR). Considerable progress in therapy has been achieved, but diagnosis and monitoring of InsR-aAb remains a challenge.

OBJECTIVE

This work aimed to establish a robust in vitro method for InsR-Ab quantification.

METHODS

Longitudinal serum samples from patients with TBIR at the National Institutes of Health were collected. A bridge-assay for InsR-aAb detection was established using recombinant human insulin receptor as bait and detector. Monoclonal antibodies served as positive controls for validation.

RESULTS

The novel assay proved sensitive, robust, and passed quality control. The measured InsR-aAb from TBIR patients was associated with disease severity, decreased on treatment, and inhibited insulin signaling in vitro. Titers of InsR-aAb correlated positively to fasting insulin in patients.

CONCLUSION

Quantification of InsR-aAb from serum samples via the novel in vitro assay enables identification of TBIR and monitoring of successful therapy.

Novel Use of Dasiglucagon, a Soluble Glucagon Analog, for the Treatment of Hyperinsulinemic Hypoglycemia Secondary to Suspected Insulinoma: A Case Report

INTRODUCTION

Hyperinsulinemic hypoglycemia is the most common cause of persistent hypoglycemia in children and adults. In adolescents and adults, hyperinsulinemic hypoglycemia is most frequently caused by an insulin-producing tumor.

CASE PRESENTATION

A 17-year-old, previously healthy male presented with recurrent and severe episodes of hypoglycemia. Diagnostic evaluation was consistent with hyperinsulinemic hypoglycemia, and an insulinoma was suspected. Multiple imaging studies and surgical exploration failed to identify a lesion. Over the course of months, the patient was found to be refractory to conventional medical interventions.

CONCLUSION

Upon approval from the US Food and Drug Administration and the Institutional Review Board, the patient was treated with dasiglucagon, a novel soluble glucagon analog, under a single-patient Investigational New Drug. The patient has tolerated the medication and has been able to achieve appropriate glycemic control.

Hypoglycemia as a potential risk for patients taking clopidogrel: A systematic review and meta-analysis

BACKGROUND

Clopidogrel is a cornerstone antiplatelet drug used in cardiovascular, cerebrovascular, and peripheral artery diseases. The sulfhydryl group of clopidogrel metabolite could induce insulin autoimmune syndrome (IAS) with hypoglycemia as the major symptom. Discontinuing clopidogrel and substituting it with ticagrelor has been revealed as an effective treatment in previous studies. Since hypoglycemia serves as a risk factor for cardiovascular and cerebrovascular events, we aimed to determine the association between hypoglycemia/IAS and clopidogrel and to investigate whether clopidogrel is a modifiable and causal risk factor of hypoglycemia/IAS.

METHODS

MEDLINE, Embase, Cochrane databases, and clinical trial registries were searched for randomized controlled trials (RCTs) of clopidogrel from inception to 28 February 2022. RCTs comparing clopidogrel with placebo or other antiplatelet drugs were eligible if meeting the inclusion criteria: 1) clopidogrel was administrated 75 mg qd orally as a long-term antiplatelet prescription at least for months, and 2) hypoglycemia-inducible drugs were not used in the control arm. One investigator abstracted articles and performed a quality assessment. Uncertainties were resolved by discussions with two investigators independently. Odds ratio (OR) and risk difference (RD) were calculated and performed with subgroup analyses. The pre-specified protocol was registered in PROSPERO (CRD42022299622).

RESULTS

Six trials with 61,399 participants in total fulfilled the criteria and were included in the meta-analysis. Clopidogrel might not be associated with higher hypoglycemia odds (OR 0.95, 95% CI 0.65 to 1.40). However, Asian participants (p = 0.0437) seemed more likely to develop clopidogrel-associated hypoglycemia. Clopidogrel-associated hypoglycemia occurred at the highest rate of 0.03% (RD -0.00023, 95% CI -0.00077 to 0.00031), and this increased to 0.91% (RD 0.00210, 95% CI -0.00494 to 0.00914) in an aging population and to 0.18% (RD 0.00040, 95% CI -0.00096 to 0.00177) when Asian ratio of the population was elevated.

CONCLUSIONS

We raise the concern that clopidogrel might be a modifiable and causal risk factor of hypoglycemia. The Asian population might be more vulnerable and need additional care.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero, identifier CRD42022299622.

Hirata's disease (insulin autoimmune syndrome) following envenomation by a common krait

Snakebite envenomation is known to cause local as well as systemic haematological, myotoxic and neurological effects. Adverse effects on the endocrine system following envenomation are rarely reported. Hirata's disease, also known as insulin autoimmune syndrome (IAS) is a rare disorder that causes hypoglycaemia due to excessive production of insulin autoantibodies. This report describes a rare case of IAS which developed in a snakebite victim following envenomation by a common krait and antivenom treatment. The patient was initially treated with dextrose and corticosteroids, although plasmapheresis was required to reduce the concentration of insulin antibodies and normalise the patient's glucose level. The patient then made an uneventful recovery without permanent sequelae. This report demonstrates the impacts of envenomation by a common krait on developing Hirata's disease and creates awareness among clinicians who treat snakebite envenomation.

A typical presentation of type B insulin resistance syndrome with isolated hypoglycaemia and suppressed insulin

Type B insulin resistance syndrome is a rare autoimmune disorder affecting glucose homeostasis characterised by the presence of serum autoantibodies to the insulin receptor. Typically, these patients present with severe insulin resistance although a mixed hyperglycaemic and hypoglycaemic phenotype may also occur, as can an exceptionally rare isolated hypoglycaemia presentation. The classic biochemical pattern comprises elevated insulin levels despite significant hypoglycaemia. We report an adult man presenting with isolated hypoglycaemia and suppressed serum insulin and C-peptide levels. He demonstrated evidence of autoimmunity with positive antinuclear antibodies, reactive lymphadenopathy and cytopaenias but did not meet the criteria for systemic lupus erythematosus and underlying malignancy was not identified despite extensive investigation. Insulin receptor antibodies were present. Treatment with prednisone led to resolution of hypoglycaemia, with no recurrence after 36 months of follow-up. However, 42 months after initial presentation, he represented with high-grade lymphoma.

Whole-exome sequencing analysis of a Japanese patient with hyperinsulinemia and liver dysfunction

Hyperinsulinemia is often observed in obese subjects because of insulin resistance, but it may occur in nonobese subjects with unknown etiology. A 72-year-old man was admitted to our hospital for the examination of hyperinsulinemia, reactive hypoglycemia, and liver dysfunction. The patient’s body mass index was 23.7 kg/m², but he had an elevated visceral fat area (125 cm²). His laboratory data showed mildly elevated liver enzymes, whereas plasma fasting glucose and serum insulin levels were 91 mg/dL and 52.3 μU/mL, respectively. In a 75-g oral glucose tolerance test, the serum insulin level reached the highest value of 1124 μU/mL at 180 minutes. There was no obvious etiology except for mild liver steatosis shown by liver biopsy. We suspected genetic abnormalities related to hyperinsulinemia. We performed whole-exome sequencing (WES) analyses and identified a heterozygous nonsense variant p.R924X in the insulin receptor (INSR) gene, a novel heterozygous missense variant p.V416M in the AKT1 gene, and a novel hemizygous missense variant p.R310Q in the PHKA2 gene, which is the causative gene of hepatic injury as glycogen storage disease type IX. It was speculated that the INSR gene variant, in addition to visceral fat accumulation, was the main cause of hyperinsulinemia and reactive hypoglycemia, and the remaining 2 variants were also partly responsible for hyperinsulinemia. WES analysis revealed candidate gene variants of hyperinsulinemia and hepatic-type glycogenosis. Thus, WES analysis may be a useful tool for clarifying the etiology when unexplained genetic pathophysiological conditions are suspected.

Practical Clinical Applications of Islet Autoantibody Testing in Type 1 Diabetes

BACKGROUND

The distinction between type 1 diabetes (T1D) and type 2 diabetes (T2D) is extremely important for the choice of therapy, body weight and dietary management, screening for coexistent autoimmune diseases and comorbidities, anticipated prognosis, and risk assessment in relatives. Not uncommonly, the presentation of the patient may not allow an unambiguous discrimination between T1D and T2D. To help resolve this challenge, the detection of islet autoantibodies can support the diagnosis of T1D.

CONTENT

The presence of islet autoantibodies in a person with diabetes indicates an autoimmune etiology therefore establishing the diagnosis of T1D. Presently 5 islet autoantibodies are available for routine clinical use: islet cell cytoplasmic autoantibodies (ICA), insulin autoantibodies (IAA), glutamic acid decarboxylase autoantibodies (GADA), insulinoma associated-2 autoantibodies (IA-2A), and zinc transporter-8 autoantibodies (ZnT8A). There are caveats to the selection of which islet autoantibodies should be measured. Islet autoantibodies can also predict the development of T1D. Therefore, once safe and effective therapies are available to prevent T1D, islet autoantibody testing is expected to become a routine part of medical practice. A very rare cause of autoimmune diabetes is the type B insulin resistance syndrome resulting from antagonistic autoantibodies to the insulin receptor. Rarely hypoglycemia can result from agonistic insulin receptor autoantibodies, or high-titer IAA causing the autoimmune insulin syndrome (i.e., Hirata disease).

SUMMARY

In summary, autoimmune causes of dysglycemia are increasing in clinical importance requiring the scrutiny of laboratorians. The determination of islet autoantibodies can greatly aid in the diagnosis and the prediction of T1D.

Hormone Immunoassay Interference: A 2021 Update

Immunoassays are powerful qualitative and quantitative analytical techniques. Since the first description of an immunoassay method in 1959, advances have been made in assay designs and analytical characteristics, opening the door for their widespread implementation in clinical laboratories. Clinical endocrinology is closely linked to laboratory medicine because hormone quantification is important for the diagnosis, treatment, and prognosis of endocrine disorders. Several interferences in immunoassays have been identified through the years; although some are no longer encountered in daily practice, cross-reaction, heterophile antibodies, biotin, and anti-analyte antibodies still cause problems. Newer interferences are also emerging with the development of new therapies. The interfering substance may be exogenous (e.g., a drug or substance absorbed by the patient) or endogenous (e.g., antibodies produced by the patient), and the bias caused by interference can be positive or negative. The consequences of interference can be deleterious when clinicians consider erroneous results to establish a diagnosis, leading to unnecessary explorations or inappropriate treatments. Clinical laboratories and manufacturers continue to investigate methods for the detection, elimination, and prevention of interferences. However, no system is completely devoid of such incidents. In this review, we focus on the analytical interferences encountered in daily practice and possible solutions for their detection or elimination.

Insulin Receptor Autoantibody-mediated Hypoglycemia in a Woman With Mixed Connective Tissue Disease

Autoantibodies to the insulin receptor are rare and typically cause severe insulin resistance and hyperglycemia, a condition termed type B insulin resistance. Uncommonly, antibodies to the insulin receptor can cause hypoglycemia. We present the case of a woman who developed recurrent severe hypoglycemia and myopathy, was found to have insulin receptor autoantibodies and mixed connective tissue disease, and had resolution of hypoglycemia with immunosuppression. A 55-year-old woman with a history of obesity, hypertension, and prior hemorrhagic stroke presented with recurrent severe hypoglycemia. A diagnostic fast resulted in hypoinsulinemic hypoketotic hypoglycemia. Adrenal function was intact. Progressive myopathy had developed simultaneously with her hypoglycemia, and rheumatologic evaluation revealed mixed connective tissue disease. The plasma acylcarnitine profile was normal, extensive oncologic evaluation including insulin-like growth factor 2 measurement was unrevealing, and anti-insulin antibody testing was negative. Ultimately, anti-insulin receptor antibodies were found to be present. The patient was treated with glucocorticoids and rituximab. Eight weeks after initiation of immunosuppression, the insulin receptor antibody titer had decreased and hypoglycemia had resolved. Eight months after diagnosis, the patient remained free of severe hypoglycemia despite tapering of glucocorticoids to a near-physiologic dose. Though antibodies to the insulin receptor typically cause severe insulin resistance, this patient had no evidence of insulin resistance and instead presented with recurrent severe hypoglycemia, which responded to glucocorticoids and rituximab. The diagnosis of insulin receptor antibody–mediated hypoglycemia is rare but should be considered in patients with systemic autoimmune disease, including mixed connective tissue disease, in the appropriate clinical context.

[Insulin autoimmune syndrome : A rare, but important differential diagnosis of hypoglycemia]

Eine 69-jährige Patientin mit rezidivierenden schweren Hypoglykämien wurde zur weiteren Diagnostik der Medizinischen Hochschule Hannover zugewiesen. Zuvor hatte die Patientin nach einem Stenting, das aufgrund einer peripheren arteriellen Verschlusskrankheit (pAVK) erforderlich war, mit einer Clopidogreleinnahme begonnen. Das Vorliegen eines Insulinoms und eines paraneoplastischen Syndroms wurde ausgeschlossen. Trotz niedrig normaler Blutzuckerkonzentrationen fanden sich erhöhte Insulin- und Insulinautoantikörperkonzentrationen. Diagnostiziert wurde ein Insulinautoimmunsyndrom, a.e. (am ehesten) ausgelöst durch vorausgegangene Clopidogreleinnahme. Eine Behandlung mithilfe der Immunadsorption wurde initiiert; diese erzielte eine signifikante Reduktion der hypoglykämischen Ereignisse und ein anhaltendes Therapieansprechen über 3 Monate.

An African American Male Patient with Rare Type B Insulin Resistance Syndrome

Syndromes of severe insulin resistance can result from mutations in the insulin receptor gene or autoantibodies to the insulin receptor. The type B syndrome of insulin resistance results from autoantibodies to the insulin receptor and occurs predominantly in women under age 50 years. Here we report on a 64 year old African American man with systemic lupus erythematosus (SLE) and acanthosis nigricans who had severe insulin resistance requiring up to 5000 units of insulin per day. He was diagnosed with type B insulin resistance syndrome based on his clinical presentation and demonstration of autoantibodies to the insulin receptor in his serum. This case study underscores the importance of assaying for autoantibodies to the insulin receptors especially in African American patients with severe insulin resistance and diabetes requiring excessive doses of insulin, in the setting of an autoimmune disease like SLE. It also behooves reference laboratories to develop and offer this assay because these patients have a very high mortality.

Insulinoma With Concomitant Insulin Antibodies

Objective

The coexistence of insulinoma and insulin antibodies is extremely rare. The aim of this novel case report is to inform physicians of the possibility of an insulinoma with concomitant insulin antibodies.

Methods

In this report, we describe a patient with symptomatic hypoglycemia confirmed with a 72-hour fast, who was subsequently found to have an insulinoma with concomitant elevation in his immunoglobulin G insulin antibody titer.

Results

The patient presented with initial symptoms of diaphoresis, confusion, and disorientation and was found unresponsive by a bystander. He had a fingerstick blood glucose of 36 mg/dL (reference 74-99 mg/dL), without exogenous insulin or sulfonylurea use. His symptoms resolved with administration of glucose. He was subsequently admitted for a 72-hour fast in which he developed neuroglycopenic symptoms 4 hours into the fast with fingerstick glucose of 47 mg/dL and serum glucose of 44 mg/dL (reference 74-99 mg/dL), C-peptide of 10.8 ng/mL (reference 0.5-2.7 ng/mL), insulin level of 106 μIU/mL (reference <25 μIU/mL), and a proinsulin level of 675 pmol/mL (reference <22 pmol/mL). His insulin-to-C-peptide ratio was 0.20, in which a ratio <1 is indicative of an insulinoma. Endoscopic ultrasound demonstrated a 16 x 11 mm biopsy-proven neuroendocrine tumor. He was found to have a high titer insulin antibody titer at 2.4 U/mL (reference <0.4 U/mL), was started on prednisone, and underwent successful radiofrequency ablation. He was able to be successfully tapered off steroids without recurrence.

Conclusion

The coexistence of insulinoma with insulin antibodies is novel, and to our knowledge, has never been published.

A novel approach to a rare case of non-islet cell hypoglycaemia

SUMMARY

Insulin autoimmune syndrome (IAS) is a rare cause of non-islet cell hypoglycaemia. Treatment of this condition is complex and typically involves long-term use of glucocorticoids. Immunotherapy may provide an alternative in the management of this autoimmune condition through the suppression of antibodies production by B-lymphocyte depletion. We present a case of a 62-year-old male, with refractory hypoglycaemia initially presenting with hypoglycaemic seizure during an admission for acute psychosis. Biochemical testing revealed hypoglycaemia with an inappropriately elevated insulin and C-peptide level and no evidence of exogenous use of insulin or sulphonylurea. Polyethylene glycol precipitation demonstrated persistently elevated free insulin levels. This was accompanied by markedly elevated anti-insulin antibody (IA) titres. Imaging included CT with contrast, MRI, pancreatic endoscopic ultrasound and Ga 68-DOTATATE position emission tomography (DOTATATE PET) scan did not reveal islet cell aetiology for hyperinsulinaemia. Maintenance of euglycaemia was dependent on oral steroids and dextrose infusion. Complete resolution of hypoglycaemia and dependence on glucose and steroids was only achieved following treatment with plasma exchange and rituximab.

LEARNING POINTS

Insulin autoimmune syndrome (IAS) should be considered in patients with recurrent hyperinsulinaemic hypoglycaemia in whom exogenous insulin administration and islet cell pathologies have been excluded. Biochemical techniques play an essential role in establishing high insulin concentration, insulin antibody titres, and eliminating biochemical interference. High insulin antibody concentration can lead to inappropriately elevated serum insulin levels leading to hypoglycaemia. Plasma exchange and B-lymphocyte depletion with rituximab and immunosuppression with high dose glucocorticoids are effective in reducing serum insulin levels and hypoglycaemia in insulin autoimmune syndrome (IAS). Based on our observation, the reduction in serum insulin level may be a better indicator of treatment efficacy compared to anti-insulin antibody (IA) titre as it demonstrated greater correlation to the frequency of hypoglycaemia and to hypoglycaemia resolution.

Carcinoid Syndrome and Hyperinsulinemic Hypoglycemia Associated with Neuroendocrine Neoplasms: A Critical Review on Clinical and Pharmacological Management

The carcinoid syndrome (CS) and hyperinsulinemic hypoglycemia (HH) represent two of the most common clinical syndromes associated with neuroendocrine neoplasms (NENs). The former is mainly related to the serotonin secretion by a small bowel NEN, whereas the latter depends on an insulin hypersecretion by a pancreatic insulinoma. Both syndromes/conditions can affect prognosis and quality of life of patients with NENs. They are often diagnosed late when patients become strongly symptomatic. Therefore, their early detection and management are a critical step in the clinical management of NEN patients. A dedicated and experienced multidisciplinary team with appropriate therapeutic strategies is needed and should be encouraged to optimize clinical outcomes. This review aims to critically analyze clinical features, evidence and treatment options of CS and HH and therefore to improve their management.

Natural Autoimmunity to the Thyroid Hormone Monocarboxylate Transporters MCT8 and MCT10

The monocarboxylate transporters 8 (MCT8) and 10 (MCT10) are important for thyroid hormone (TH) uptake and signaling. Reduced TH activity is associated with impaired development, weight gain and discomfort. We hypothesized that autoantibodies (aAb) to MCT8 or MCT10 are prevalent in thyroid disease and obesity. Analytical tests for MCT8-aAb and MCT10-aAb were developed and characterized with commercial antiserum. Serum samples from healthy controls, thyroid patients and young overweight subjects were analyzed, and prevalence of the aAb was compared. MCT8-aAb were additionally tested for biological effects on thyroid hormone uptake in cell culture. Positive MCT8-aAb and MCT10-aAb were detected in all three clinical cohorts analyzed. MCT8-aAb were most prevalent in thyroid patients (11.9%) as compared to healthy controls (3.8%) and overweight adolescents (4.2%). MCT8-aAb positive serum reduced T4 uptake in cell culture in comparison to MCT8-aAb negative control serum. Prevalence of MCT10-aAb was highest in the group of thyroid patients as compared to healthy subjects or overweight adolescents (9.0% versus 4.5% and 6.3%, respectively). We conclude that MCT8 and MCT10 represent autoantigens in humans, and that MCT8-aAb may interfere with regular TH uptake and signaling. The increased prevalence of MCT8-aAb and MCT10-aAb in thyroid disease suggests that their presence may be of pathophysiological relevance. This hypothesis deserves an analysis in large prospective studies.

Analysis of the clinical characteristics of insulin autoimmune syndrome induced by alpha-lipoic acid

WHAT IS KNOWN AND OBJECTIVE

Alpha-lipoic acid (ALA) is widely used as a dietary supplement and antiageing agent. Insulin autoimmune syndrome (IAS) is the most serious adverse reaction reported with the use of ALA. The purpose of this study was to explore the clinical characteristics of ALA-induced IAS and provide a scientific reference for clinical diagnosis, treatment and prevention.

METHODS

We collected literature on IAS cases induced by ALA for retrospective analysis in Chinese and English.

RESULTS AND DISCUSSION

The median age of 37 patients (28 females and 9 males) was 61 years (range 32-82). The symptoms occurred at night and in the early morning (60.7%), in the late postprandial period (50.0%) or after fasting (35.7%), within hours in some patients and up to 2 months in others after stopping ALA or during medication treatment. Autonomic nervous system symptoms (81.1%) and neurological hypoglycaemia (64.9%) are the main clinical manifestations of hypoglycaemia. The blood glucose concentration at the onset of hypoglycaemia was 2.19 mmol/L (median, range 1.09-3.52), the insulin concentration was ≥100 μIU/ml (94.6%), and the C-peptide concentration was ≤20 ng/ml (83.3%). Testing for IgG insulin autoantibodies (IAAs) was positive in 37 patients. Pancreatic imaging was unremarkable on computed tomography (CT), magnetic resonance imaging (MRI) and abdominal sonography. Hypoglycaemia disappeared within 5 days to 8 months after withdrawing ALA alone or using corticosteroid treatment. IAA turned negative in 7 months (median; range 2-36). Follow-up showed no recurrent hypoglycaemic episodes at 7.25 months (median; range 1-36).

WHAT IS NEW AND CONCLUSION

ALA-induced IAS is a clinically rare autoimmune disease with hypoglycaemia that occurs during medication treatment or after drug withdrawal that should be treated promptly.

A Novel Type of Extreme Insulin Resistance: Nonhypoglycemic Insulin Autoimmune Syndrome

CONTEXT

Extreme insulin resistance is caused by genetic defects intersecting with the insulin action pathway or by the insulin receptor antibodies. Insulin autoimmune syndrome (IAS) is not considered one of the causes of extreme insulin resistance.

OBJECTIVE

This work aimed to expand the current knowledge of extreme insulin resistance and to propose the diagnostic criteria and management strategy of a novel type of extreme insulin resistance.

METHODS

A patient with IAS never experienced hypoglycemia but had persistent hyperglycemia and extreme insulin resistance with treatment with 200 U of intravenous insulin per day. Immunoreactive insulin (IRI), free insulin, and total insulin were measured. The ratio of free insulin to total insulin (insulin-free ratio, IFR) was calculated.

RESULTS

Extreme insulin resistance has not been reported to be caused by IAS. At admission, IRI and free insulin were undetectable in our patient; total insulin was more than 20 160 pmol/L; and the IFR was lower than 0.03% (control, 90.9%). After adding 500 U porcine insulin to the precipitate containing insulin antibodies, the IRI was still undetectable. Since the patient started glucocorticoid therapy, the free insulin has gradually increased to 11.16 pmol/L, his total insulin has decreased to 5040 pmol/L, and the IFR has increased to 18.26%. Intravenous insulin was stopped, with good glycemic control.

CONCLUSION

High-affinity insulin autoantibodies with a large capacity can induce a novel type of extreme insulin resistance characterized by extremely high total insulin and very low free insulin levels. The IFR can be used to evaluate therapeutic effects.

Uncooked cornstarch for the prevention of hypoglycemic events

Hypoglycemia is a pathological condition characterized by a low plasma glucose concentration associated with typical autonomic and/or neuroglycopenic symptoms, and resolution of these symptoms with carbohydrate consumption. Hypoglycemia is quite common in clinical practice, particularly in insulin-treated patients with diabetes and in other inherited or acquired conditions involving the regulation of glucose metabolism. Beyond symptoms that might strongly affect the quality of life, hypoglycemia can lead to short- and long-term detrimental consequences for health. Hypoglycemia can be prevented by appropriate changes in dietary habits or by relevant modifications of the drug treatment. Several dietary approaches based on the intake of various carbohydrate foods have been tested for hypoglycemia prevention; among them uncooked cornstarch (UCS) has demonstrated a great efficacy. In this narrative review, we have summarized the current evidence on the UCS usefulness in some conditions characterized by high hypoglycemic risk, focusing on some inherited diseases -i.e. glycogen storage diseases and other rare disorders - and acquired conditions such as type 1 diabetes, postprandial hypoglycemia consequent to esophageal-gastric or bariatric surgery, and insulin autoimmune syndrome. We also considered the possible role of UCS during endurance exercise performance. Lastly, we have discussed the dose requirement, the side effects, the limitations of UCS use, and the plausible mechanisms by which UCS could prevent hypoglycemia.

Hirata's Disease: Rare Cause of Hypoglycaemia in Caucasian Male

Insulin autoimmune syndrome or Hirata's disease is an extremely rare condition leading to hypoglycaemia of variable severity due to autoantibodies against insulin. We present the first case documented in the Czech Republic.

Tumor-Induced Hypoglycemia: An Unusual Case Report and Review of Literature

Objective

To describe a rare case of pheochromocytoma presenting with hypoglycemia.

Methods

We describe a rare case of pheochromocytoma presenting with a hypoglycemic seizure. Our article includes our differentials, work up, and management.

Results

Our patient had non–islet-cell tumor hypoglycemia that was non-insulin mediated, as noted by low insulin levels. His hypoglycemia was likely multifactorial and mediated by different mechanisms. We describe the rare case and review the causes of tumor-induced hypoglycemia.

Conclusion

Pheochromocytomas can rarely present with hypoglycemia and are associated with a poor prognosis.

Clinical and Laboratory Aspects of Insulin Autoantibody-Mediated Glycaemic Dysregulation and Hyperinsulinaemic Hypoglycaemia: Insulin Autoimmune Syndrome and Exogenous Insulin Antibody Syndrome

Autoimmune glycaemic dysregulation and hyperinsulinaemic hypoglycaemia mediated by insulin autoantibodies is an increasingly recognised but controversial phenomenon described in both exogenous insulin naïve (insulin autoimmune syndrome) and exposed (exogenous insulin antibody syndrome) individuals. There has been a significant proliferation of case reports, clinical studies and reviews in the medical literature in recent years which have collectively highlighted the discrepancy between experts in the field with regard to the nomenclature, definition, proposed pathophysiology, as well as the clinical and biochemical diagnostic criteria associated with the condition. The essential characteristics of the condition are glycaemic dysregulation manifesting as episodes of hyperglycaemia and unpredictable hyperinsulinaemic hypoglycaemia associated with high titres of endogenous antibodies to insulin. Although the hypoglycaemia is often life-threatening and initiation of targeted therapies critical, the diagnosis is often delayed and attributable to various factors including: the fact that existence of the condition is not universally accepted; the need to exclude surreptitious causes of hypoglycaemia; the diverse and often complex nature of the glycaemic dysregulation; and the challenge of diagnostic confirmation. Once confirmed, the available therapeutic options are expansive and the reported responses to these therapies have been variable. This review will focus on our evolving understanding, and the associated diagnostic challenges - both clinical and laboratory - of this complex condition.

Long-term follow-up of insulin autoimmune syndrome in an elderly patient

An 84-year-old man was admitted to our hospital. His blood glucose level was 20 mg/dL. Since laboratory tests showed high titers of insulin antibodies, insulin autoimmune syndrome (IAS) was diagnosed. In　order to avoid hypoglycemia, steroids can be effective in the long-term management of IAS in elderly patients.

A Lean Lady With Acanthosis Nigricans and Uncontrolled Diabetes Mellitus

A 47-year-old Asian Indian woman presented with uncontrolled hyperglycaemia and osmotic symptoms despite multiple oral antidiabetic medications and insulin. She had a history of recurrent oral ulcers, profound weight loss, and intermittent fever for one and a half years before the presentation. She had severe acanthosis nigricans, although her body mass index (BMI) was 14.6 kg/m².

Her blood glucose remained uncontrolled despite very large dosages of intravenous insulin (more than 12,000 units daily). Evaluation for possible underlying collagen vascular diseases and malignancies were negative. Her serum insulin levels were high. She tested negative for anti-insulin antibodies but positive for anti-insulin-receptor antibodies. She improved with a pulse dose of intravenous methylprednisolone but relapsed within one month. A second pulse dose was given following which a complete remission of diabetes and regression of acanthosis was observed.

Type B insulin resistance, a rare cause of severe insulin resistance, may respond favourably to immunosuppressive therapy with high-dose methylprednisolone.

Pathophysiology of diabetes: An overview

Diabetes mellitus is a chronic heterogeneous metabolic disorder with complex pathogenesis. It is characterized by elevated blood glucose levels or hyperglycemia, which results from abnormalities in either insulin secretion or insulin action or both. Hyperglycemia manifests in various forms with a varied presentation and results in carbohydrate, fat, and protein metabolic dysfunctions. Long-term hyperglycemia often leads to various microvascular and macrovascular diabetic complications, which are mainly responsible for diabetes-associated morbidity and mortality. Hyperglycemia serves as the primary biomarker for the diagnosis of diabetes as well. In this review, we would be focusing on the classification of diabetes and its pathophysiology including that of its various types.

Insulin autoimmune syndrome

SUMMARY

Insulin autoimmune syndrome (Hirata's disease) is a disorder caused by development of autoantibodies to insulin and manifested by hypoglycaemic syndrome. The overwhelming majority of physicians do not include it in the differential diagnosis of hypoglycaemic states because of a misconception of an extremely low prevalence of this condition. This results in unnecessary drug therapy and unjustified surgical interventions in patients that otherwise would be successfully treated conservatively. This disease is strongly associated with certain alleles of the HLA gene. In most cases, this condition develops in predisposed individuals taking drugs containing sulfhydryl groups. Formation of autoantibodies to insulin may be observed in patients with other autoimmune disorders, as well as in those with multiple myeloma or monoclonal gammopathy of undetermined significance. This paper presents the first Russian case report of insulin autoimmune syndrome in an adult patient.

LEARNING POINTS

Insulin autoimmune syndrome, Hirata's disease, anti-insulin antibodies, and hypoglycaemia.

Management of Insulin Autoimmune Hypoglycaemia: Single-centre experience from Western India with systematic review of world literature

BACKGROUND

Awareness about Insulin Autoimmune Hypoglycaemia (IAH) and its management remains limited.

METHODOLOGY

We describe two cohorts: Cohort 1 (n = 7) included patients with IAH from a tertiary care centre in India and Cohort 2 (n = 294) included systematic review of published English literature from PubMed. They were compared with our insulinoma patients (n = 41).

RESULTS

Cohort 1 included seven female patients where two had drugs (carbimazole and thiocolchicoside) as triggering factors. Except for one patient requiring oral prednisolone, others had spontaneous remission. The unique features from our series are being first case series of IAH from India and reporting of second case of thiocolchicoside triggered IAH. Cohort 2 had 294 patients identified from 149 publications. Mean age was 54 ± 19 years. Thirty-five different triggers were identified from 160 cases. Antithyroid drugs were most common triggers in Japanese patients and most common HLA allele was DRB1*0406, while it was alpha-lipoic acid and HLA DRB1*0403 in non-Asians. Serum Insulin >100 µIU/mL and insulin to C-peptide molar ratio (ICMR) >0.25 had specificity of 100% and 97.5%, respectively, for IAH as compared to insulinoma. 56% patients had remission with complex carbohydrate diet and trigger removal while 43% required immunosuppressants. 70% achieved remission within 6 months.

CONCLUSIONS

Middle age remains most common age group. Sulfhydryl drugs are most common triggers. Serum Insulin >100 µIU/mL and ICMR > 0.25 in critical sample are good predictors for diagnosis of IAH, which needs to be confirmed by IAA. Conservative management with dietary modification and trigger removal usually suffices in majority. Rests need immunosuppressants.

Rare causes of hypoglycemia in adults

Hypoglycemia is defined by a low blood glucose level associated to clinical symptoms. Hypoglycemia may be related to treatment of diabetes, but also to drugs, alcohol, critical illness, cortisol insufficiency including hypopituitarism, insulinoma, bariatric or gastric surgery, pancreas transplantation or glucagon deficiency, or may be surreptitious. Some hypoglycemic episodes remain unexplained, and genetic, paraneoplastic and immune causes should be considered. Genetic causes may be related to endogenous hyperinsulinism and to inborn errors of metabolism (IEM). Endogenous hyperinsulinism is related to monogenic congenital hyperinsulinism, and especially to mutations of the glucokinase-activating gene or of insulin receptors, both characterised by postprandial hypoglycemia with major hyperinsulinism. In adulthood, IEM-related hypoglycemia can persist in a previously diagnosed childhood disease or may be a presenting sign. It is suggested by systemic involvement (rhabdomyolysis after fasting or exercising, heart disease, hepatomegaly), sometimes associated to a family history of hypoglycemia. The timing of hypoglycemic episodes with respect to the last meal also helps to orientate diagnosis. Fasting hypoglycemia may be related to type 0, I or III glycogen synthesis disorder, fatty acid oxidation or gluconeogenesis disorder. Postprandial hypoglycemia may be related to inherited fructose intolerance. Exercise-induced hyperinsulinism is mainly related to activating mutation of the SLC16A1 gene. Besides exceptional ectopic insulin secretion, paraneoplastic causes involve NICTH (Non-Islet-Cell Tumour Hypoglycemia), caused by Big-IGF2 secretion by a large tumour, with low blood levels of insulin, C-peptide and IGF1. Autoimmune causes involve antibodies against insulin (HIRATA syndrome), especially in case of Graves' disease, or against the insulin receptor. Medical history, timing, and insulin level orientate the diagnosis.

Insulin Autoimmune Syndrome: A Case of Clopidogrel-induced Autoimmune Hypoglycemia

CONTEXT

Insulin autoimmune syndrome (IAS) is characterized by hyperinsulinemic hypoglycemia with elevated anti-insulin antibodies. Most commonly observed in the Japanese population, elsewhere it is rare and associated with autoimmune diseases, plasma cell dyscrasias, or sulfhydryl group medications. The active metabolite of clopidogrel has a sulfhydryl group and here we report a case of clopidogrel-induced IAS.

CASE DESCRIPTION

A 67-year-old man was admitted with severe hyperinsulinemic hypoglycemia requiring continuous intravenous infusion of 10% dextrose to sustain euglycemia. His symptoms of hypoglycemia had started after commencing dual antiplatelet therapy (including clopidogrel) for ischemic heart disease 9 months earlier. The hypoglycemia was associated with elevated insulin, proinsulin, c-peptide, and anti-insulin antibody titers as well as the HLA-DRB1*04 haplotype. Multiple localizing studies were negative for an insulinoma. A diagnosis of IAS was thus made. Clopidogrel cessation, oral dexamethasone, and diazoxide therapy were not sufficient to safely wean the dextrose infusion. Plasma exchange was ultimately effective.

CONCLUSIONS

This case highlights a case of severe IAS. Given the ubiquity of clopidogrel, IAS should be remembered as a rare adverse effect.

Receptor autoimmunity: diagnostic and therapeutic implications

Receptor autoimmunity is one of the ways in which autoimmune diseases appear in humans. Graves' disease, myasthenia gravis, idiopathic membranous nephropathy, and autoimmune acute encephalitis are the major autoimmune diseases belonging to this particular group. Receptor autoimmune disease are dependent on the presence of autoantibodies directed against cell-surface antigens, namely TSH receptor in thyrocytes, acetylcholine receptor in neuromuscular junction, phospholipase 2 receptor in podocytes, and NMDA receptor in cortical neurons. In this article we outline the distinctive features of receptor autoimmunity and the specific relationship between the autoimmunology laboratory and the presence/concentration of autoantibodies. Some immunological features distinguish receptor autoimmunity. Anti-receptor autoantibody pathologies are considered T cell-dependent, B-cell-mediated autoimmune disorders: the knowledge about the presence of circulating and/or localized autoantibodies to target organs and identification of autoantigens involved in the autoimmune reaction is of paramount importance. Due to the close correlation between the concentration of anti-receptor autoantibodies, the autoimmune target of some cell-surface receptors and the intensity of symptoms, the measurement of these immunoglobulins has become central to diagnose autoimmune diseases in all affected patients, not just in clinically dubious cases. The measurement of autoantibodies is also relevant for differential diagnosis of autoimmune and non-autoimmune forms with similar symptoms. From the methodological point of view, quantitative immunoassay methods of measurement should be preferred over semi-quantitative ones, for the capacity of the first class of methods to define precisely the reference ranges and decision levels overcoming the measurement uncertainty of semi-quantitative methods.

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.

Insulin Autoimmune Syndrome After Exposure to Clopidogrel: A Case Report

BACKGROUND

Insulin autoimmune syndrome (IAS) is a rare cause of hypoglycemia that is characterized by hyperinsulinemia, hypoglycemia, and a high autoantibody titer. About 50% of patients with IAS have taken a medication containing sulfhydryl (-SH) groups. We present a case of IAS that developed after taking clopidogrel, a drug with an active metabolite that contains an SH-group.

CASE REPORT

IAS was suspected in a 63-year-old Chinese man because of high concentrations of insulin and C-peptide during hypoglycemic episodes, and positivity for anti-insulin autoantibody (IAA). During his first episode of hypoglycemia, no trigger medication was identified and prednisone therapy was effective. However, imaging examination revealed a colonic carcinoma and the patient was discharged to undergo surgery. He had no episodes of hypoglycemia for 10 weeks after discontinuation of the prednisone, but then hypoglycemia recurred. A review of his medication revealed that he had taken a 10-day course of clopidogrel just before the recurrence. Therefore, a specialized multidisciplinary team consisting of endocrinologists, dieticians, and clinical pharmacists took charge of his management. Prednisone therapy was restarted and tapered off over 16 weeks. The patient also consumed small, frequent, low-carbohydrate meals and was instructed to avoid trigger medications. No further episodes of hypoglycemia were detected. His insulin and C-peptide concentrations and his anti-IAA index normalized during the follow-up period.

CONCLUSION

SH-group-containing drugs might induce or exacerbate hypoglycemia in patients with a history of IAS. Furthermore, patients with IAS can benefit from multidisciplinary team management. We suggest herein an evaluation process for patients suspected of IAS.

Insulin Autoimmune Syndrome in a 25-Year-Old, Previously Healthy Kuwaiti Man

Insulin autoimmune syndrome (IAS) is a disease characterized by hyperinsulinaemic hypoglycaemia associated with autoantibodies against endogenous insulin. We have described a case of a 25-year-old, previously healthy Kuwaiti man who was admitted to the Mubarak Al-Kabeer hospital with a history of recurrent hypoglycaemia. The patient revealed that he had taken several different injectable anabolic steroids and growth hormone with oral amino acids and other tablets (fat burners) for bodybuilding in the last two months. He denied knowingly using insulin or insulin analogues. The patient had elevated fasting insulin level (>301 uIU/mL) and elevated insulin autoantibodies (>100.0 IU/mL). After appropriate work-up, he was diagnosed with IAS. After treatment with prednisolone (1 mg/kg/day), the patient had complete recovery. In patients with repeated hypoglycaemia, IAS should be considered in the differential diagnosis. Glucocorticoid therapy can be effective for the treatment of hypoglycaemia in patients with IAS.

Endogenous hyperinsulinism: diagnostic and therapeutic difficulties

Endogenous hyperinsulinism is an abnormal clinical condition that involves excessive insulin secretion, related in 55% of cases to insulinoma. Other causes are possible such as islet cell hyperplasia, nesidioblastosis or antibodies to insulin or to the insulin receptor. Differentiation between these diseases may be difficult despite the use of several morphological examinations. We report six patients operated on for endogenous hyperinsulinism from 1^st January 2000 to 31^st December 2015. Endogenous hyperinsulinism was caused by insulinoma in three cases, endocrine cells hyperplasia in two cases and no pathological lesions were found in the last case. All patients typically presented with adrenergic and neuroglycopenic symptoms with a low blood glucose level concomitant with high insulin and C-peptide levels. Computed tomography showed insulinoma in one case out of two. MRI was carried out four times and succeeded to locate the lesion in the two cases of insulinoma. Endoscopic ultrasound showed one insulinoma and provided false positive findings three times out of four. Intra operative ultrasound succeeded to localize the insulinoma in two cases but was false positive in two cases. Procedures were one duodenopancreatectomy, two left splenopancreatectomy and two enucleations. For the sixth case, no lesion was radiologically objectified. Hence, a left blind pancreatectomy was practised but the pathological examination showed normal pancreatic tissue. Our work showed that even if morphological examinations are suggestive of insulinoma, other causes of endogenous hyperinsulinism must be considered and therefore invasive explorations should be carried out.

Insulin Autoimmune Syndrome Diagnosis and Therapy in a Single Chinese Center

PURPOSE

Insulin autoimmune syndrome (IAS) is a relatively rare cause of hypoglycemia characterized by endogenous hyperinsulinism and autoantibodies against endogenous insulin despite no prior exposure to exogenous insulin. We present a series of IAS cases and describe the clinical characteristics of these cases.

METHODS

The medical records of inpatients with the final diagnosis of IAS were collected from August 2007 to August 2017 in Peking Union Medical College Hospital. Clinical characteristics and laboratory test results were summarized. The results of serum glucose, insulin, true insulin, and C-peptide testing during 5-h oral glucose tolerance tests were also summarized. Circulating immune complexes were assessed qualitatively by precipitation with polyethylene glycol (PEG) in some patients.

FINDINGS

Sixteen patients were included in this study. Insulin autoimmune antibody test results were found positive in 12 patients and weakly positive in 1 patient. Nine patients had an insulin to C-peptide molar ratio >1, whereas 6 patients had an insulin to C-peptide molar ratio <1. Circulating immune complexes were verified in all 4 patients who had been assessed with PEG. During 5-h oral glucose tolerance tests, the C-peptide level responded earlier to the glucose tolerance and had a shorter peak value period compared with insulin, although C-peptide's fluctuation still lagged behind the glucose fluctuation. Three patients presented with self-limited disease courses or limited disease course after discontinuing use of the sulfhydryl group drugs. Some patients' symptoms were relieved after small frequent meals, and some were relieved after taking acarbose. Only 3 patients took glucocorticoids as the anti-immune therapy.

IMPLICATIONS

The insulin to C-peptide molar ratios were not consistently >1 in patients with confirmed diagnoses of IAS in our study, which suggested the low sensitivity of insulin to C-peptide molar ratio to detect IAS. The therapy in our study also revealed the self-limited disease course of IAS, and despite the effectiveness of anti-immunity therapy, convenient therapy, such as frequent small meals and adding acarbose, performed well in many patients.