Persistent Insulin Autoimmune Syndrome in a Caucasian Male in the Absence of Triggers

Insulin autoimmune syndrome (IAS) or Hirata disease is a rare condition presenting as recurrent hypoglycemia, and associated with elevated insulin levels in the presence of insulin autoantibodies (IAAs) in patients who were never exposed to exogenous insulin and with no evidence of pancreatic abnormalities. IAS is much more frequent in East Asians, especially the Japanese population, compared to the lower incidence in Caucasians. However, it can be associated with other autoimmune diseases or drug use like methimazole and alpha-lipoic acid (ALA). We report a case of a 47-year-old Caucasian male presenting with a 12-month history of worsening episodes of fasting and post-prandial hypoglycemia associated with symptoms of dizziness, tremors, palpitations, and unconsciousness associated with hypoglycemia. Symptoms resolved with the administration of carbohydrate-containing foods, establishing Whipple's triad. At an outside facility, he had initial labs that showed elevated insulin levels (141 µU/ml) with normal glucose, C-peptide, and proinsulin levels, but there was no availability of an IAA lab assay. Given his symptoms, severity, and frequency of hypoglycemia, he was admitted to the hospital for a 72-hour fast, which showed the lowest glucose level of 64 mg/dl with inappropriately high insulin of 22.2 µU/ml, low C-peptide of 0.57 ng/ml, and undetectable proinsulin of <1.6 pmol/L, but with IAA being >50 U/ml (0.0-0.4 U/ml). He was treated with intensive dietary counseling with a low-carbohydrate diet and prednisone 20 mg twice daily initially. Additionally, he could not tolerate octreotide, diazoxide, and acarbose due to side effects. He is currently on prednisone 10 mg daily and nifedipine with no further hypoglycemic episodes, but still has a high IAA of >50 U/ml and serum insulin levels of 70-112 µU/ml. Our case highlights the importance of recognizing hypoglycemia and checking for IAA levels as first-line diagnostic tests, in the absence of which there could be a delay in diagnosis and leading to unnecessary lab and imaging testing. Our case is unique since it happened in a Caucasian without any prior exposure to a triggering factor and has not undergone self-remission yet, which happens in most of IAS cases.

An Unusual Case of Hypoglycemia in a Non-diabetic Individual due to Hirata Disease

Hypoglycemia is common in diabetic populations using insulin or insulin secretagogues, but rare in non-diabetics. A 60-year-old non-diabetic male presented with repeated episodes of abnormal behavior persisting for 10-15 minutes for seven days, associated with sweating, intense hunger, and relief on food intake, with no history of insulin or secretagogue intake, with stable vitals and normal systemic examination. Laboratory tests during attacks revealed low blood sugar, high serum insulin, and normal C-peptide levels, with no evidence of pancreatic or extrapancreatic hyperinsulinism, and serum anti-insulin antibody levels >100 U/ml. Based on these results, he was diagnosed with autoimmune insulin syndrome (AIS). Treatment with low-carb meals, oral prednisolone, and acarbose led to the resolution of symptoms. Hirata syndrome, though rare in India, requires consideration as a differential diagnosis to avoid unnecessary invasive procedures.

A review on nondiabetic hypoglycemia from various causes: Case series report

RATIONALE

Hypoglycemia is common in patients with glucose regulation disorders and related diabetic treatments but is rare in nondiabetic patients. Severe hypoglycemia can cause harm to patients' cognition, consciousness, central nervous system, cardiovascular and cerebrovascular system, and even death. However, the most fundamental way to control hypoglycemia is to identify the cause and deal with the primary disease. This article introduces 3 cases of nondiabetic hypoglycemia with different causes, aiming to improve our understanding of nondiabetic hypoglycemia and improve the ability of early diagnosis and differential diagnosis.

PATIENT CONCERNS

Case 1 is a 19-year-old female with a history of recurrent coma, and magnetic resonance imaging and endoscopic ultrasound of the pancreas suggest insulinoma. Case 2 is a 74-year-old male with a history of viral hepatitis, and computerized tomography shows multiple nodules in the liver, which is diagnosed as liver cancer. Case 3 is a 39-year-old female with a history of taking methimazole, who tested positive for insulin antibodies, and was diagnosed with insulin autoimmune syndrome.

DIAGNOSIS

All 3 patients were diagnosed with nondiabetic hypoglycemia, but the causes varied, and included insulinoma, non-islet cell tumor-induced hypoglycemia, and insulin autoimmune syndrome.

INTERVENTIONS

Case 1 underwent pancreatic tail resection; case 2 refused anti-tumor treatment and received glucose injections for palliative treatment only; and case 3 stopped taking methimazole.

OUTCOMES

After surgery, the blood sugar in case 1 returned to normal, and the blood sugar in case 2 was maintained at about 6.0 mmol/L. The symptoms of hypoglycemia gradually improved in case 3 after stopping the medication.

LESSONS

Non-diabetic hypoglycemia requires further examination to clarify the cause, and the correct differential diagnosis can provide timely and effective treatment, improving the patient's prognosis.

Insulin autoimmune syndrome

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Diagnosis and treatment of anti-insulin antibody-mediated labile glycaemia in insulin-treated diabetes

AIMS

Anti-insulin antibodies in insulin-treated diabetes can derange glycaemia, but are under-recognised. Detection of significant antibodies is complicated by antigenically distinct insulin analogues. We evaluated a pragmatic biochemical approach to identifying actionable antibodies, and assessed its utility in therapeutic decision making.

METHODS

Forty people with insulin-treated diabetes and combinations of insulin resistance, nocturnal/matutinal hypoglycaemia, and unexplained ketoacidosis were studied using broad-specificity insulin immunoassays, polyethylene glycol (PEG) precipitation and gel filtration chromatography (GFC) with or without ex vivo insulin preincubation.

RESULTS

Twenty-seven people had insulin immunoreactivity (IIR) below 3000 pmol/L that fell less than 50% after PEG precipitation. Insulin binding by antibodies in this group was low and judged insignificant. In 8 people IIR was above 3000 pmol/L and fell by more than 50% after PEG precipitation. GFC demonstrated substantial high molecular weight (HMW) IIR in 7 of these 8. In this group antibodies were judged likely significant. In 2 people immunosuppression was introduced, with a good clinical result in one but only a biochemical response in another. In 6 people adjustment of insulin delivery was subsequently informed by knowledge of underlying antibody. In a final group of 5 participants IIR was below 3000 pmol/L but fell by more than 50% after PEG precipitation. In 4 of these GFC demonstrated low levels of HMW IIR and antibody significance was judged indeterminate.

CONCLUSIONS

Anti-insulin antibodies should be considered in insulin-treated diabetes with unexplained glycaemic lability. Combining immunoassays with PEG precipitation can stratify their significance. Antibody depletion may be beneficial, but conservative measures often suffice.

Late-Onset Type 1 Diabetes Mellitus and Unexplained Subcutaneous Lesions

Nodular fasciitis is considered a reactive lesion of connective tissue originating from the proliferation of fibroblasts and myofibroblasts. Nodular fasciitis preponderantly localizes within the higher extremities, trunk, head, and neck. We are presenting a report on the case of a 38-year-old Navy pilot who developed nodular lesions in the area of the sternum and upper back and was diagnosed concomitantly with insulin-dependent diabetes mellitus (type 1 diabetes). The patient was treated for diabetic ketoacidosis using intensive insulin therapy protocol, and the nodules were surgically excised. He was discharged from the hospital four weeks later. In our presentation, we intend to highlight the essential characteristics of this rare lesion through a review of the literature and to identify an attainable link between the development of type 1 diabetes and nodular fasciitis.

A Case of Insulin Autoimmune Syndrome Accompanied With Systemic Joint Pain: A Case Report

Insulin autoimmune syndrome (IAS) is a rare disorder characterised by autoantibodies against endogenous insulin that cause spontaneous hypoglycemic episodes. Here, we present the case of a 66-year-old male with polyarticular pain and dizziness that was initially suspected to be an insulinoma. However, further testing confirmed the presence of IAS. The patient's joint pain fluctuated but improved with the control of blood glucose levels. Although the direct relationship between IAS and joint pain is not well established, individuals with a single autoimmune disorder may develop concurrent autoimmune conditions. Joint pain is prevalent in patients with autoimmune diseases. Although hypoglycemia may cause muscle cramps due to stress responses, direct musculoskeletal damage is uncommon. This case underscores the importance of differential diagnosis, particularly in differentiating between pancreatic cancer and the benign proliferation of pancreatic B cells. Elevated levels of insulin autoantibodies confirm IAS, whereas pancreatic cancer may manifest various symptoms and elevated cancer antigens (CA) 19-9. General physicians should comprehensively investigate hypoglycemia cases, particularly those associated with pancreatic enlargement, and continually monitor for potential malignancies.

Autoimmune Hypoglycemia With Anti-Insulin Autoantibodies in an Eighty-One-Year-Old Woman Without Apparent Risk Factors

Background/Objective

Insulin autoimmune syndrome (IAS) is a very rare cause of hypoglycemia presenting with recurrent fasting or postprandial hypoglycemia episodes with elevated serum insulin levels and insulin autoantibodies. The objective of this case is to highlight the importance of considering IAS in patients with hypoglycemia.

Case Report

We present a case of an 81-year-old female who presented with symptoms of hypoglycemia. She was found to have hyperinsulinemic hypoglycemic episodes without any apparent risk factors for IAS. She had positive-insulin autoantibodies in her serum leading to the diagnosis of IAS. Acutely, hypoglycemia was managed with D50 pushes, oral glucose, and glucagon injection.

Discussion

Patients who present with hypoglycemia due to endogenous hyperinsulinemia should have IAS considered as a possible differential diagnosis. Insulin autoantibodies are measured as the gold standard diagnostic test for IAS. Foods with a low glycemic index are the primary treatment for IAS.

Conclusion

This case presentation highlights the importance of considering IAS as a differential diagnosis in patients presenting with hypoglycemia secondary to hyperinsulinemia, even in the absence of apparent risk factors.

A Case of Insulin Autoimmune Syndrome in an Indian Male Taking Alpha-Lipoic Acid

Insulin autoimmune syndrome [IAS, Hirata disease (HD)] is a rare cause of recurrent spontaneous hypoglycemic episodes, characterized by high serum insulin levels and high titers of autoantibodies against endogenous insulin. We report a case of a previously healthy Indian male presenting with recurrent episodes of hypoglycemia with no prior exposure to exogenous insulin. Regular glucose monitoring was done. Laboratory tests showed insulin >1000 μIU/mL and C-peptide levels of 12.8 ng/ml. The patient had high titers of insulin autoantibodies (IAA) (>100 units/mL; normal range: <10 units/mL), which indicated a diagnosis of IAS. The patient was consuming alpha-lipoic acid; sulfhydryl-containing compounds have been linked to IAS. This case report highlights the importance of IAA titers in first-line investigations for hypoglycemia in a non-diabetic patient with strikingly high blood insulin levels and discusses the potential relationship between IAS and alpha-lipoic acid.

An Uncommon Case of Recurrent Hypoglycemic Episodes in a Healthy Non-diabetic Male: Insulin Autoimmune Syndrome

Insulin autoimmune syndrome is a rare cause of recurrent hypoglycemic episodes that can mimic various other pathological problems leading to unnecessary diagnostic assessments and interventions. Here, we report a case of a healthy non-diabetic male in his 50s presenting with recurrent episodes of hypoglycemia with no prior exposure to exogenous insulin. During a 72-hour fasting test, his glucose levels reached 22 mg/dl within less than three hours. The lab tests showed insulin of 1000 μIU/mL and C-peptide of 4.99 ng/ml. On further evaluation, high titers of insulin autoantibodies (IAA) >100 U/ml (normal = <10 U/ml) were consistent with insulin autoimmune syndrome diagnosis. This case thus highlights the importance of including IAA titers in first-line investigations for hypoglycemia in a non-diabetic patient with strikingly high blood insulin levels.

Long-term follow-up of methimazole-associated insulin autoimmune syndrome: a rare case report

Insulin autoimmune syndrome (IAS) is a rare cause of hypoglycemia and is characterized by the presence of insulin autoantibodies and fasting or late postprandial hypoglycemia. The number of reports on the association of long-term follow-up of IAS in China is limited. We herein report a case of drug-induced IAS in a 44-year-old Chinese woman. She had been taking methimazole for Graves' disease and had subsequently presented with recurrent hypoglycemic episodes. Laboratory assessments on admission revealed that her serum insulin level was significantly elevated (>1000 µIU/mL) and that she was positive for serum insulin autoantibody, leading to a diagnosis of IAS. Human leukocyte antigen DNA typing identified *04:06/*09:01:02, an immunogenetic determinant associated with IAS. After treatment with prednisone for 2 months, the hypoglycemic episodes disappeared, her serum insulin level gradually declined, and her insulin antibody levels became negative. Clinicians should be aware of the potential for methimazole to trigger autoimmune hypoglycemia in people with a genetic predisposition.

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.

Hypoglycemic Coma Caused by Methimazole-Induced Insulin Autoimmune Syndrome, a Case Study

Islet autoimmune syndrome (IAS) is an autoimmune disease caused by high concentrations of insulin autoantibodies (IAA) in the blood. It is characterized by hyperinsulinemia and spontaneous hypoglycemia. The incidence of IAS is low, and the hypoglycemia symptom is usually mild. Hence, the severe manifestations (up to seizures and coma) are rarely reported. Here, we reported two cases of Graves' disease who developed insulin autoimmune syndrome after methimazole treatment. The patients exhibited sudden hypoglycemic coma after receiving methimazole treatment for approximately 2 or 6 months. The patients' serum glucose levels were below 2.8 mmol/L, and laboratory tests showed high levels of serum insulin and high titers of insulin autoantibodies. Patient 1 discontinued methimazole treatment and the hypoglycemic symptoms disappeared after 7 days. However, patient 2 experienced severe hypoglycemia after discontinuation of methimazole, and the patient condition improved after glucocorticoid therapy. He developed thyroid storm during the treatment, and his condition improved after receiving standard treatment procedures for thyroid storm. To the best of our knowledge, this is the first case report of IAS in Graves' disease with thyroid storm.

Comparison of patient characteristics between East Asian and non-East Asian patients with insulin autoimmune syndrome

OBJECTIVE

Insulin autoimmune syndrome (IAS) is the third most common cause of spontaneous hypoglycaemia in Japan but very rare in the rest of the world. We aimed to identify factors, which are associated with the occurrence of IAS and which may differ between East Asian and non-East Asian patients.

DESIGN

A PubMed search using the search terms 'insulin autoimmune syndrome' and 'Hirata disease' revealed a total of 287 reports of IAS cases, including one previously unpublished own case.

RESULTS

Mean age (±standard deviation) was 52 ± 19 years in East Asian and 54 ± 21 years in non-East Asian patients (p > .05). In both groups, there were more females. Mean body mass index was lower in East Asian than in non-East Asian patients (23.0 ± 4.3 vs. 27.1 ± 5.6 kg/m² , p < .0001). Postprandial hypoglycaemia was more common in non-East Asian patients (p < .05). East Asian patients took more frequently antithyroid medications and non-East Asian patients angiotensin-converting enzyme (ACE) inhibitors (both p < .0001). Graves' disease and other autoimmune diseases were more frequently observed in East Asian patients (both p < .01). Parameters of glucose metabolism were comparable in both groups, independent of diabetes diagnosis (p > .05), except for insulin that was higher in East Asian compared to non-East Asian metabolically healthy patients (p < .01). Human leukocyte antigen (HLA)-DRB1*0406 was the most frequent HLA-type in East Asian patients (p < .0001), whereas DRB1*0403 and *0404 were more frequent in non-East Asian patients (both p < .05). Non-East Asian patients received more secondary treatments, including plasmapheresis and rituximab, whereas medication discontinuation was more common in East Asian patients (all p < .05). Outcome was similar in both groups (p > .05).

CONCLUSIONS

Factors associated with IAS markedly differ between East Asian and non-East Asian patients, with autoimmune disorders, particularly Graves' disease, antithyroid medications, and HLA-DRB1*0406 more prevalent in East Asian patients and cardiovascular and plasma cell diseases, ACE inhibitors and HLA-DRB1*0403 more prevalent in non-East Asian patients.

Pseudo-pheochromocytoma due to obstructive sleep apnea: a case report

SUMMARY

Obstructive sleep apnea (OSA) is a condition of intermittent nocturnal upper airway obstruction. OSA increases sympathetic drive which may result in clinical and biochemical features suggestive of pheochromocytoma. We present the case of a 65-year-old male with a 2.9-cm left adrenal incidentaloma on CT, hypertension, symptoms of headache, anxiety and diaphoresis, and persistently elevated 24-h urine norepinephrine (initially 818 nmol/day (89-470)) and normetanephrine (initially 11.2 µmol/day (0.6-2.7)). He was started on prazosin and underwent left adrenalectomy. Pathology revealed an adrenal corticoadenoma with no evidence of pheochromocytoma. Over the next 2 years, urine norepinephrine and normetanephrine remained significantly elevated with no MIBG avid disease. Years later, he was diagnosed with severe OSA and treated with continuous positive airway pressure. Urine testing done once OSA was well controlled revealed complete normalization of urine norepinephrine and normetanephrine with substantial symptom improvement. It was concluded that the patient never had a pheochromocytoma but rather an adrenal adenoma with biochemistry and symptoms suggestive of pheochromocytoma due to untreated severe OSA. Pseudo-pheochromocytoma is a rare presentation of OSA and should be considered on the differential of elevated urine catecholamines and metanephrines in the right clinical setting.

LEARNING POINTS

Obstructive sleep apnea (OSA) is a common condition among adults. OSA may rarely present as pseudo-pheochromocytoma with symptoms of pallor, palpitations, perspiration, headache, or anxiety. OSA should be considered on the differential of elevated urine catecholamines and metanephrines, especially in patients with negative metaiodobenzylguanidine (MIBG) scan results.

Insulin autoimmune syndrome caused by esomeprazole in a Chinese patient

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Scientific opinion on the relationship between intake of alpha-lipoic acid (thioctic acid) and the risk of insulin autoimmune syndrome

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on the relationship between alpha-lipoic acid (ALA) and the risk of insulin autoimmune syndrome (IAS). The Panel was also asked to advise on the dose below which ALA added to foods is not expected to cause IAS. A review of all possible adverse effects associated with consumption of ALA was not requested. This mandate refers to the procedure under Article 8(2) of Regulation (EC) No 1925/2006 on addition of vitamins, minerals and certain other substances to foods. No pre-established rule exists for the evaluation of the safety of foods when classical toxicity tests cannot be used, e.g. for autoimmune diseases. Published scientific evidence was retrieved through comprehensive literature searches, particularly 49 case reports in which IAS developed following ALA consumption. In all cases, IAS resolved after a few weeks to months when ALA was discontinued. No publication linking the intake of ALA naturally occurring in foods to IAS was identified. The Panel concludes that the consumption of ALA added to foods, including food supplements, is likely to increase the risk of developing IAS in individuals with certain genetic polymorphisms, who cannot be readily identified without genetic testing. The plausible mechanism of such an effect has not yet been fully elucidated. The incidence of IAS in Europe is low and likely lower than in Japan where it has been estimated to be 0.017 per 100,000 inhabitants in 2017-2018. Considering the limited data available, the risk associated with the development of IAS following ALA consumption cannot be quantified precisely. An ALA dose below which IAS is not expected to occur is likely to vary between individuals and cannot be determined from the available data.

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.

A combination of plasma exchange and steroids in the treatment of a-lipoic acid-induced insulin autoimmune syndrome

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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.

Methimazole-induced insulin autoimmune syndrome in Graves' disease with hypokalemia: A case report and literature review

The patient in the present case report, a 27-year-old man, was diagnosed with Graves' disease and hypokalemia. The patient was treated with methimazole and intermittent potassium supplementation. Following treatment, the patient was still suffering from fatigue, accompanied by palpitations, a hand tremor, fear of heat and sweating. Hypoglycemia was revealed by monitoring fingertip blood glucose levels. The laboratory investigations indicated that serum insulin levels were significantly elevated (>1,000 µIU/ml), the test for serum insulin autoantibody (IAA) was positive, and insulin autoimmune syndrome (IAS) was diagnosed. Following symptomatic treatment, the patients insulin levels decreased, and the hypoglycemia episode was gradually relieved. Hypoglycemia may be prone to missed diagnosis in patients with Graves' disease and hypokalemic periodic paralysis. Monitoring fingertip blood glucose level is a convenient and feasible method to detect hypoglycemia. Furthermore, serum insulin and IAA detection should be assessed to exclude or confirm IAS.

Analysis of the clinical characteristics of insulin autoimmune syndrome induced by methimazole

WHAT IS KNOWN AND OBJECTIVE

The number of case reports of insulin autoimmune syndrome (IAS) induced by methimazole (MMI) is increasing. The purpose of this study is to explore the clinical characteristics and provide a scientific reference for clinical diagnosis, treatment and prevention.

METHODS

The literature on IAS cases and case series induced by MMI in Chinese and English was collected for retrospective analysis.

RESULTS AND DISCUSSION

A total of 106 patients (males 33, females 73) were described in the Chinese and English literature. The median age of patients with IAS induced by MMI was 37 years (range 15-76) occurring during both regular and irregular MMI therapy or after resumption of medication. The onset of symptoms occurred at night or early morning, within days in some and up to 6 months in others; the symptoms were neuropathic in 65.31% and related to the autonomic nervous system in 33.67%. Blood glucose concentration in samples presumably taken during the hypoglycaemic phase was 1.7 mmol/L (median; range 0.03-4.7); insulin concentrations were elevated ≥100 mU/L (ref range) and associated with low C-peptide levels (<10 μg/L; ref range). Tests for IgG insulin autoantibodies (IAA) were positive in 104 patients (98.02%) and negative in two patients (1.98%). The 75-g oral glucose tolerance test (OGTT) showed impaired glucose tolerance and diabetic curves. Pancreatic imaging was unremarkable on computed tomography (CT), magnetic resonance imaging (MRI) and ultrasound. Withdrawal of MMI alone or with corticosteroid treatment reduced hypoglycaemic episodes within days to 3 months. IAA decreased and became negative in 3 months (median; range 1-12). Follow-up showed no recurrent hypoglycaemic episodes at 5 months (median; range 1-60).

WHAT IS NEW AND CONCLUSION

Methimazole-induced IAS is a clinically rare autoimmune disease with hypoglycaemia that occurs during medication treatment that should be treated promptly.

Insulin autoimmune syndrome: A rare cause of hypoglycemia

Insulin autoimmune syndrome (IAS) is a rare cause of hyperinsulinemic hypoglycemia. It is due to autoantibodies to endogenous insulin in person who has never been sensitized to insulin by injections. IAS is a third leading cause of spontaneous hypoglycemia in Japan and it is increasingly being recognized worldwide in non-Asian population. However, we report a case of IAS in Asian male. A certain class of medication called sulfhydryl compounds have been shown to sometimes cause IAS. Recently a compound called alpha lipoic acid (ALA) has been associated with an increased risk of developing IAS. ALA is sometimes used for dieting purposes. We report a case of 36-year-old Indian male presented with symptoms of dizziness and feeling of hunger with sweating, noted to have low blood sugars on multiple occasions. There is a definite history of ALA compound intake as dietary supplements with multivitamins. Subsequently, he was diagnosed as a case of recurrent hypoglycemia from IAS due to ALA intake and managed accordingly.

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.

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.

Insulin autoimmune syndrome - time to remember

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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.

Pitfalls in the diagnosis of insulin autoimmune syndrome (Hirata's disease) in a hypoglycemic child: a case report and review of the literature

Background Insulin autoimmune syndrome (IAS) is a rare cause of hyperinsulinemic hypoglycemia (HH) not addressed as a potential differential diagnosis in current pediatric guidelines. We present a case of IAS in a child with no previous history of autoimmune disease, no previous intake of triggering medications and absence of genetic predisposition. Case presentation A 6-year-old boy presented with recurrent HH (blood glucose of 26 mg/dL [1.4 mmol/L] and insulin of 686 μU/mL). Abdominal imaging was normal. After multiple therapeutic failures, we hypothesized misuse of exogenous insulin and factitious hypoglycemia. Council of Guardianship had the child separated from his mother, but insulin levels remained high. A chromatography test was then performed which showed high titers of endogenous insulin autoantibody (IAA) with early dissociation from the insulin molecule. The human leukocyte antigen (HLA) test showed a DRB1 *13:01/*08:02 genotype. The patient was advised to control food intake and physical activity routines. During a 5-year follow-up, hypoglycemic episodes were sparse, despite high insulin levels. Conclusions Misdiagnosis of IAS with factitious hypoglycemia may happen if IAS is not considered as a differential diagnosis, leading to potential traumatic consequences. Further efforts should be made to increase awareness of IAS as a differential diagnosis of hypoglycemia and to include it in pediatric guidelines.

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.

Insulin autoimmune syndrome as a cause of recurrent hypoglycemia in a carbimazole user: a case report from Nepal

Insulin autoimmune syndrome (IAS) is a rare cause of nondiabetic hypoglycemia characterized by hyperinsulinemia and autoantibodies to endogenous insulin without prior exposure to exogenous insulin. We report a drug-induced case of IAS in a 59-year-old Nepalese female. She had been taking carbimazole for Graves’ disease and later presented with recurrent episodes of hypoglycemia, with laboratory findings of low blood glucose, increased molar ratio of insulin to C-peptide, and elevated autoantibodies to insulin. IAS should be considered while evaluating hypoglycemia to prevent unwarranted invasive procedures and surgical interventions.

Insulin autoimmune syndrome: Three case reports

RATIONALE

Insulin autoimmune syndrome (IAS) is a rare endocrine disease characterized by repeated fasting hypoglycemia or episodes of hypoglycemia late after meals, elevated serum insulin, and positivity for insulin autoantibody (IAA) or insulin receptor antibody (IRA). We summarize the clinical manifestations and treatment experiences of 3 patients with IAS.

PATIENT CONCERNS

One patient with >20-year history of type 2 diabetes mellitus had irregular episodes of hypoglycemia 2 years of after treatment with insulin. Another patient with a 6-year history of type 2 diabetes mellitus presented irregular episodes of hypoglycemia after 6 months of treatment with insulin. One patient with a history of Graves' disease showed hypoglycemia after administration of thiamazole.

DIAGNOSIS

Serum islet cell antibody (ICA) and glutamic acid decarboxylase antibody (GADA) were negative, while antibody insulin autoantibodies were positive in all the 3 patients. Two patients demonstrated diabetes mellitus after an oral glucose tolerance test, while one had normal glucose tolerance. Furthermore, serum insulin levels significantly elevated and did not matched C peptide levels. No abnormalities were found on enhanced MRI of the pancreas, and all 3 patients were clinically diagnosed with IAS.

INTERVENTIONS

In case one, insulin aspart 30 injection was withdrawn after admission. In addition, the patient was prescribed sublingual acarbose 3 times daily. Two weeks after admission, prednisone acetate was administered orally once daily at night. In case 2, insulin aspart 30 injection was withdrawn after admission, the patient was prescribed sublingual acarbose 3 times daily with a meal. Five days after admission, oral prednisone acetate was administered once daily at night. In case 3, oral propylthiouracil was prescribed and thiamazole withdrawn after admission, and the patient consumed an extra meal before sleeping.

OUTCOMES

At the 3-month follow-up visit, the hypoglycemic episodes had disappeared, serum insulin levels were significantly decreased, and insulin antibody (IA) levels were no longer detectable in all 3 patients.

LESSONS

For those patients with high-insulin hypoglycemia, IAA should be evaluated if serum insulin concentrations are inconsistent with C peptide levels. Therapeutically, a lower dose of glucocorticoids with more appropriate medication timing can be used to achieve good results.

Therapeutic plasma exchange normalizes insulin-mediated response in a child with type 1 diabetes and insulin autoimmune syndrome

BACKGROUND

Insulin autoimmune syndrome (IAS), characterized by glycemic dysregulation and life-threatening hypoglycemia, can occur in patients with type 1 diabetes (T1D). Diagnostic confirmation is complex but important in order to ensure timely initiation of definitive therapy.

AIMS

We aimed to quantitate the degree of immunoglobulin-insulin complex (IIC) formation and its effects on glycemic control in a patient with T1D and IAS compared with T1D and non-T1D controls and before and after therapeutic plasma exchange (TPE).

MATERIALS & METHODS

The prospective descriptive study was conducted between June 2015 and December 2015 in a quaternary children's hospital in Brisbane, Australia. Percent Free "Immunoreactive" Insulin (%FII) as assessed by polyethylene glycol precipitation studies and its relationship to plasma glucose and serum insulin concentration.

RESULTS

Samples from the patient with T1D and IAS demonstrated lower mean %FII compared to T1D (23.8 ± 2.0 vs 52.0 ± 6.7; P < .0001) and non-T1D (23.8 ± 2.0 vs 102.9 ± 2.7; P < .0001) controls. This was associated with loss of glycemic predictability and frequent severe hypoglycemia. TPE increased %FII (23.8 ± 2.0 before TPE vs 83.6 ± 2.5 after TPE, P < .0001) and reestablished plasma glucose responsiveness to exogenous insulin.

DISCUSSION

IAS should be considered in T1D patients with unexplained glycemic instability and hypoglycemia. The laboratory plays an integral diagnostic role.

CONCLUSION

TPE is an effective method for removing IICs and normalizing insulin-mediated glucose responses.

Insulin autoimmune syndrome in a pregnant female: A rare case report

RATIONALE

Insulin autoimmune syndrome (IAS) is an uncommon disorder characterized by hyperinsulinemic hypoglycemia related to insulin-binding autoantibodies. To the best of our knowledge, we report the first case of a pregnant female with IAS.

PATIENT CONCERNS

The 26-year-old patient with Graves disease and 10 weeks pregnant developed IAS after approximately 6 months treatment with methimazole. The patient exhibited recurrent spontaneous hypoglycemia.

DIAGNOSES

On evaluation, laboratory findings detected both high fasting insulin (>1000 mIU/L) and insulin autoantibodies. An oral glucose tolerance test showed elevated insulin concentrations with disproportionately elevated C-peptide levels. The imaging study showed nomasslesionsinthepancreas,and the patient was clinically diagnosed with IAS.

INTERVENTIONS

The patient had an abortion, discontinued methimazole and switched to oral prednisone (30 mg once daily) and propylth- iouracil (100 mg 3 times daily) for 3 months.

OUTCOMES

At the 3-month follow-up visit, hypoglycemic episodes had disappeared and insulin antibody levels were no longer detectable.

LESSONS

We have described this case and reviewed the relevant literature concerning diagnosis and treatment of IAS. Importantly, this case indicates that clinicians should view pregnancy as another factor of hypoglycemia in IAS.

"Riding High on Low Fuel" - Our Experience with Endogenous Hyperinsulinemic Hypoglycemia

INTRODUCTION

Endogenous hyperinsulinemic hypoglycemia (EHH) is a condition in which the insulin levels are inappropriately high in the presence of low plasma glucose.

MATERIALS AND METHODS

We did a retrospective analysis of case records of those patients admitted and evaluated for EHH from June 2004 to June 2016 in our center, excluding those that were diagnosed with reactive hypoglycemia. We collected data regarding demographics, clinical presentation, laboratory results, localization techniques, and treatment administered.

RESULTS

Sixteen patients who were admitted for evaluation based on history suggestive of repeated hypoglycemic episodes were included in the study. All but one pregnant patient was subjected to a supervised fast in the hospital. All patients developed hypoglycemia (defined using Whipple's triad) within the first 24 h. Three patients had autoimmune hypoglycemia which differed significantly from insulinoma-mediated hypoglycemia in certain clinical and laboratory parameters. They were older in age with marked fluctuations in the 24 h glucose profile ranging from frank hypoglycemia to frank hyperglycemia. The insulin levels were markedly elevated in this group of patients along with a significantly elevated insulin C peptide molar ratio (ICMR) when compared with patients with insulinoma-mediated hypoglycemia.

CONCLUSIONS

Although insulinoma is the most common cause of EHH, autoimmune hypoglycemia should be considered as a differential diagnosis, particularly in older individuals with plasma glucose values increasing to the hyperglycemic range. Degree of elevation of insulin levels and ICMR may provide additional clues. Overall, the survival and prognosis of patients with EHH are excellent.

Clopidogrel-Induced Insulin Autoimmune Syndrome: A Newly Recognized Cause of Hypoglycemia in a Patient Without Diabetes

Insulin autoimmune syndrome (IAS), defined as hyperinsulinemic hypoglycemia with high titers of anti-insulin antibodies, is frequently reported in Japanese patients but rarely observed in whites. We report in this study on a 79-year-old white male without diabetes who developed IAS following exposure to clopidogrel, a drug not previously known to cause hypoglycemia. The patient presented with recurrent symptomatic hypoglycemia. During one episode, serum glucose was 45 mg/dL, whereas insulin and C-peptide levels were 40,000 mIU/mL and 40 ng/mL, respectively. Additional studies revealed no intake of insulin or its secretagogues, whereas anti-insulin antibody titer was high (59.3 nmol/L). Although total insulin levels were consistently high, free insulin concentrations (polyethylene glycol precipitation) were appropriate for ambient glycemia. The patient was found to have HLA-DRB1*0404, a feature often reported in Japanese patients with IAS. Three weeks prior to symptom onset, he was started on clopidogrel, a drug that does not have a sulfhydryl group, but its active metabolite does. Clopidogrel was switched to a nonsulfhydryl antiplatelet agent, and glucocorticoid therapy was initiated. Shortly thereafter, the frequency of hypoglycemic episodes decreased, and glucocorticoids were tapered over the ensuing 3 months. No hypoglycemic episodes were noted during 6 months of observation after discontinuing glucocorticoids, whereas the total insulin and anti-insulin antibody levels normalized. The data indicate that IAS should be considered in the differential diagnosis of hyperinsulinemic hypoglycemia in seemingly well individuals, even when no drugs known to cause IAS were used. Clinical suspicion of IAS can avoid expensive imaging and unnecessary surgery in affected patients.

Gliclazide-Induced Insulin Autoimmune Syndrome: A Rare Case Report and Review on Literature

BACKGROUND

Insulin Autoimmune Syndrome (IAS) is a rare condition characterized by the combination of recurrent severely spontaneous hypoglycemia without evidence of exogenous insulin administration, high concentration of total serum insulin, and the presence of a high titer of insulin autoantibody (IAA). But now we describe a case with IAS caused by gliclazide and hardly occuring hypoglycemia.

CASE REPORT

A 70-year-old man with type 2 diabetes presented to our department with poor glycemic control without evidence of hypoglycemia, but the levels of serum insulin and IAA were very high. He had no exogenous insulin administration history. Switching antidiabetic therapy from gliclazide to acarbose and metformin, the patient's serum insulin level and IAA decreased gradually. Accordingly, the glycemic control improved and there was no episode of hypoglycemia.

CONCLUSION

Hence, clinicians should pay more attention to type 2 diabetic patients treated with gliclazide and detect their serum insulin concentration and IAA to exclude or diagnose IAS and perform the best therapeutic regimen to these patients.

Insulin-induced autoimmune syndrome: A case report

Insulin autoimmune syndrome (IAS) is a disease characterized by hyperinsulinemic hypoglycemia associated with autoantibodies against endogenous insulin. A 56-year-old man was admitted to Ningbo First Hospital for the treatment of spontaneous hypoglycemia. He was found to have elevated fasting insulin level (>1,000 mIU/l) and presence of insulin autoantibodies, and after appropriate workup, was diagnosed with IAS. After treating with prednisone for 2 months, his insulin level started decreasing. In patients with repeated hypoglycemia, IAS should be considered in the differential diagnosis. Prednisone may be effective for the treatment of hypoglycemia in patients with IAS.

Methimazole-induced insulin autoimmune syndrome

BACKGROUND

Hypoglycemia in a critical care setting is often multifactorial with iatrogenic insulin use, sulfonylurea (SU) use, sepsis, adrenal insufficiency and insulinoma among the common causes. Insulin autoimmune syndrome (IAS) is a rare cause of hypoglycemia characterized by the presence of insulin-binding autoantibodies to the sulfhydryl group-containing agents. We report a case of methimazole-induced IAS managed in the intensive care unit.

CASE PRESENTATION

A 76-year-old woman with a history of primary hyperthyroidism was sent from a nursing home for unresponsiveness. Vital signs were significant for hypotension (74/46) and low blood sugars. Fluid resuscitations with normal saline and 50% dextrose stabilized the blood pressure (BP) to 135/75 and her blood glucose to 264. Due to respiratory distress and septic appearance, she required emergency intubation. Nursing home medications were noted for methimazole and absence of any insulin or SU use. Empiric antibiotic treatment was started and fluid resuscitation was continued while home medications were held. Her laboratory values were significant for elevated creatinine, lactic acid, serum cortisol, C-peptide, and insulin. Her cultures, SU screen and computerized tomography (CT) scan were negative for significant findings. On day 2, in addition to 10% dextrose, octreotide was initiated for recurrent hypoglycemia. Her blood glucose (BG) continued to drop throughout the day for which she required glucagon support and a D20 infusion. By day 4, the rate of infusion was titrated up and her BG continued to drop to <60 mg/dl despite D20, octreotide and tube feeds with concentrated calories (1.5 cal/ml). Due to her declining health, her family endorsed palliative care and she was extubated. After day 11, her hypoglycemic episodes resolved and she remained endogenously euglycemic.

CONCLUSIONS

IAS is associated with methimazole use due to formation of autoantibodies to insulin after its interaction with Sulfhydryl (SH) group in methimazole. While IAS is a rare entity, it demands consideration in hypoglycemia in patients with autoimmune conditions.

Simulation of the Insulin Autoimmune Syndrome

In rare cases, the monoclonal immunoglobulin that characterizes essential monoclonal gammopathy interacts with a self-antigen with functional consequences and a resulting clinical syndrome. This event is presumably random and results from the clone of B lymphocytes making a monoclonal immunoglobulin that simulates an autoimmune antibody. Thus, by chance, the monoclonal immunoglobulin has sufficient affinity for an epitope on a normal protein that functional consequences ensue. One such rare event is the synthesis and secretion of a monoclonal immunoglobulin that binds to human insulin. Inactivation of insulin by antibody results in (1) an early postprandial hyperglycemia, (2) followed by either or both (i) a reactive overshot in insulin secretion, as a result of hypertrophied or hyperplastic islet beta cells, later falling glucose levels, and (ii) an unpredictable dissociation of insulin from the complex, and, several hours later, (3) a resultant increase in free insulin levels and severe hypoglycemia with clinical consequences, ranging from sweating, dizziness, headache, and tremors to confusion, seizures, and unconsciousness. These attacks are invariably responsive to glucose administration. This very uncommon manifestation of a monoclonal gammopathy can occur in patients with essential monoclonal gammopathy or myeloma. The monoclonal anti-insulin immunoglobulin in monoclonal gammopathy has a low affinity for insulin, but has a high capacity for insulin-binding, resulting in the syndrome of episodic hypoglycemic attacks. This phenomenon of an insulin-binding monoclonal immunoglobulin simulates the acquired insulin autoimmune syndrome, although the latter is mediated by a polyclonal antibody response in the majority of cases studied, and has linkage to HLA class II alleles.

Hypoglycemic coma due to insulin autoimmune syndrome induced by methimazole: A rare case report

Insulin autoimmune syndrome (IAS) is a rare cause of hypoglycemia characterized by the presence of insulin-binding autoantibodies and fasting or late postprandial hypoglycemia. The number of reports on the association of human leukocyte antigen (HLA) genotype with this disease in adolescents in China is limited. This is the case report of a 17-year-old female patient with Graves' disease who was treated with methimazole (MTZ). After 4 weeks of continuous MTZ treatment, the patient suffered an episode of unconsciousness during the late postprandial phase and was admitted to the hospital, where the blood glucose level was found to be 2.88 mmol/l. The symptoms were relieved following intravenous glucose administration. Imaging studies of the pancreas were unremarkable, but the laboratory investigations on admission revealed high serum levels of total insulin, associated with relatively low levels of free insulin and markedly elevated insulin autoantibody (IAB) levels. HLA testing revealed DRB1*0406/0901 and the patient discontinued MTZ and was prescribed propylthiouracil. During the long-term follow-up, the total insulin and IAB levels gradually declined. There was no other episode of hypoglycemia. Therefore, in adolescents with Graves' disease receiving antithyroid treatment with MTZ who experience hypoglycemia, the IAB levels should be assessed to exclude or confirm IAS as the underlying cause.

Recurrent hypoglycemia from insulin autoimmune syndrome

Insulin autoimmune syndrome (IAS) is an uncommon cause of hyperinsulinemic hypoglycemia characterized by autoantibodies to endogenous insulin in individuals without previous exposure to exogenous insulin. IAS is the third leading cause of spontaneous hypoglycemia in Japan, and is increasingly being recognized worldwide in non-Asian populations. We report a case of IAS in a Caucasian woman with recurrent complaints of hypoglycemia, with laboratory findings of serum glucose 2.5 mmol/L (45 mg/dL), insulin 54,930 pmol/L (7,909 μIU/mL), connecting peptide (C-peptide) 4,104 pmol/L (12.4 ng/mL), and a corresponding insulin to C-peptide molar ratio of 13.4 during a spontaneous hypoglycemic event. Autoantibodies to insulin were markedly elevated at > 50 kU/L (> 50 U/mL). IAS should be considered in the differential diagnosis of hypoglycemia in non-diabetic individuals. Distinction from insulinoma is especially crucial to prevent unwarranted invasive procedures and surgical interventions in hypoglycemic patients.

A case of autoimmune hypoglycemia outside Japan: Rare, but in the era of expanding drug-list, important to suspect

We are hereby reporting a case of a 72-year-old Indian man, who, in the absence of a detectable tumor, presented with symptomatic hypoglycemia in the postabsorptive state (3-5 h after meal). His serum levels of insulin and C-peptide were very high. He was not taking any hypoglycemic drug. Hypoglycemic episodes completely subsided after withdrawal of pentoprazole and incorporation of small frequent meals in the dietary plan. Six months after the initial presentation, the subject became free of hypoglycemic episodes. Although insulin autoimmune syndrome (IAS) is the third leading cause of spontaneous hypoglycemia in Japan, it is extremely uncommon in the Western Countries. Till 2009, more than 200 cases from Japan and as many as 58 cases outside Asia have been reported. To the best of our knowledge, this is the first case of IAS reported from India.

A novel atypical presentation of insulin autoimmune syndrome (Hirata's disease) in a child

Insulin autoimmune syndrome (IAS) or Hirata's disease is a rare cause of hyperinsulinemic hypoglycemia. We report the case of a child with a mild, atypical presentation of IAS. A previously healthy girl, aged 7 years old, developed non-ketotic fasting hypoglycemia during treatment for pneumonia. Laboratory evaluation during hypoglycemia showed the following results: serum glucose, 32 mg/dL (1.8 mmol/L); insulin, 5.6 μIU/mL (38.9 pmol/L); C-peptide, 1.4 ng/mL (0.47 nmol/L); anti-insulin antibody, 6.2% (normal, <2.4%); absence of ketonuria; and positive glucagon stimulation test result. Search for mutation in genes ABCC8, KCNJ11, GLUD1 and MEN1 was negative. Human leukocyte antigen (HLA) typing was HLA-DRB1*1104. Computed tomography scan of the abdomen showed a normal result. The patient evolved with spontaneous resolution of the hypoglycemia, within 30 days, with normalization of serum anti-insulin titers. The serum levels of insulin and anti-insulin antibodies in the patient of this report were not extremely high as previously reported. This novel, mild, or forme fruste presentation of IAS expands the previously reported spectrum of this disease.

Insulin autoimmune syndrome in a patient with ANCA-associated glomerulonephritis

The patient, a 66-year-old woman, who has been under hemodialysis due to antineutrophil cytoplasm autoantibody (ANCA)-associated glomerulonephritis since 2003, was hospitalized because of cold sweating, general fatigue, and somnolence. Hypoglycemia (43 mg/dL) with markedly elevated insulin level (1410 μU/mL) and insulin antibody was found in her serum. She was diagnosed as having insulin autoimmune syndrome. She has not taken any medication that might cause insulin autoimmune syndrome. The possible association of ANCA-associated glomerulonephritis with insulin autoimmune syndrome is discussed.