Methimazole-induced insulin autoimmune syndrome

Thyroid Hormone and Diabetes Mellitus Interplay: Making Management of Comorbid Disorders Complicated

Insulin and thyroid hormones play important roles in our body. Insulin helps regulate the glucose level while the thyroid hormones affect various cells and tissues, metabolizing protein, lipids, and glucose. Hyperthyroidism and thyrotoxicosis are potential hazards for type 2 diabetes mellitus. There is a high prevalence of hypothyroidism being more common compared to hyperthyroidism coexisting with diabetes mellitus. Thyroid hormones affect glucose metabolism through its action on peripheral tissues (gastrointestinal tract, liver, skeletal muscles, adipose tissue, and pancreas). High-level thyroid hormone causes hyperglycemia, upregulation of glucose transport, and reduction in glycogen storage. The reverse is observed during low levels of thyroid hormone along with insulin clearance. The net result of thyroid disorder is insulin resistance. Type 2 diabetes mellitus can downsize the regulation of thyroid stimulating hormones and impair the conversion of thyroxine to triiodothyronine in peripheral tissues. Furthermore, poorly managed type 2 diabetes mellitus may result in insulin resistance and hyperinsulinemia, contributing to the proliferation of thyroid tissue and an increase in nodule formation and goiter size. Although metformin proves advantageous for both type 2 diabetes mellitus and thyroid disorder patients, other antidiabetics like sulfonylureas, pioglitazone, and thiazolidinediones may have adverse effects on thyroid disorders. Moreover, antithyroid drugs such as methimazole can weaken glycemic control in individuals with diabetes. Thus, an interplay between both endocrinopathies is observed and individualized care and management of the disorder needs to be facilitated.

Insulin Autoimmune Syndrome: A Case Report Highlighting Diagnostic Pitfalls

Insulin autoimmune syndrome (IAS) is characterized by spontaneous hyperinsulinemic hypoglycemia and the presence of insulin autoantibodies in high titers without exogenous insulin use. The C-peptide level during a hypoglycemia episode is useful for differentiating spontaneous hypoglycemia. Generally, low C-peptides are suspicious for exogenous insulin administration. We report a 47-year-old male nurse who presented with an initial episode of hypoglycemia. Despite the pattern of hyperinsulinemic hypoglycemia and low C-peptide, he was diagnosed with IAS based on the presence of insulin autoantibodies. This case underscores the importance of suspecting IAS in non-diabetic adults with hypoglycemia, even in the setting of low C-peptide levels.

Safety of Antithyroid Drugs in Avoiding Hyperglycemia or Hypoglycemia in Patients With Graves' Disease and Type 2 Diabetes Mellitus: A Literature Review

Graves' disease (GD) may increase the difficulty of glucose control in patients with type 2 diabetes mellitus (T2DM). Therefore, selecting a drug with limited blood glucose side effects is an important issue in patients with T2DM and GD. Antithyroid drugs (ATDs) including propylthiouracil (PTU), methimazole, and carbimazole are commonly prescribed for the treatment of GD. Here, we review and summarize the literature from the last 10 years and discuss the effects of current ATDs used for GD for blood glucose control in patients with T2DM. A search of the literature published between January 1, 2012 and December 1, 2022 was conducted using three major medical databases: Google Scholar, Ovid Medline, and Scopus. An initial search was conducted on PubMed using the MeSH terms "propylthiouracil," "methimazole," "carbimazole," and "hyperglycemia" or "hypoglycemia" in academic databases. All articles included "Graves' disease" and "type 2 diabetes mellitus" in the title. Based on the results of previous studies, the hyperglycemic and hypoglycemic side effects of ATDs can be explained by several possible mechanisms. The most widely accepted hypothesis is that sulfhydryl group drugs (e.g., methimazole and carbimazole) cleave the disulfide bond of insulin and enhance its immunogenicity, resulting in hypoglycemia. Moreover, some reports have indicated that methimazole is associated with hypoglycemia; therefore, if the patient has a history of autoimmune diseases, it is necessary to consider whether to change drugs or actively track the production of autoimmune antibodies. In non-diabetic and diabetic patients with GD, the hyperglycemic and hypoglycemic side effects of PTU (on glycemic variation) were less than that of thiamazole. However, as relatively few reports have investigated the side effects of blood sugar changes, further research is necessary to confirm these effects. In addition to autoimmune diseases, drug side effects may need to be considered. These findings provide considerations for clinicians to select more appropriate ATDs for patients with GD and T2DM, and implement improved care guidelines.

Insulin Autoimmune Syndrome: A Systematic Review

Insulin autoimmune syndrome (IAS) is a rare endocrine disorder characterized by recurrent episodes of severe hypoglycemia, markedly elevated serum insulin, and positive insulin autoantibodies. In recent years, various countries have reported it one after another. It can be seen that we must pay attention to this disease. The diagnosis of IAS is challenging, requiring a careful workup aimed at excluding other causes of hyperinsulinemic hypoglycemia. High levels of insulin autoantibodies are found in patients, and C-peptide is not parallel to insulin, which could be diagnostic. IAS is a self-limiting disease with a good prognosis. Its treatment mainly includes symptomatic supportive treatment, such as adjusting the diet and using acarbose and other drugs to delay the absorption of glucose to prevent hypoglycemia. For patients with severe symptoms, available treatments may include drugs that reduce pancreatic insulin secretion (such as somatostatin and diazoxide), immunosuppressants (glucocorticoids, zaprin, and rituximab), and even plasma exchange to remove autoantibodies from the body. This review provides a comprehensive analysis of the epidemiology, pathogenesis, clinical manifestations, diagnosis and identification, and monitoring and treatment management of IAS.

Case report: hypoglycemia secondary to methimazole-induced insulin autoimmune syndrome in young Taiwanese woman with Graves' disease

RATIONALE

Hypoglycemia is an emergent condition with many causes, including underlying diabetes mellitus either with the use of insulin or oral anti-diabetic medications for glucose control, and organ (heart, hepatic, or renal) failure. Insulin autoimmune syndrome (IAS) can also cause hypoglycemia, however it is relatively difficult to diagnose as it is rare clinically. Although uncommon, IAS can be life threatening in patients with persistent hypoglycemia.

PATIENT CONCERN

We report the case of a 27-year-old female with underlying Graves' disease who was treated with methimazole (MTZ). After 6 weeks of treatment, she developed hypoglycemia symptoms accompanied by dizziness and cold sweating. We excluded underlying diabetes mellitus, the use of insulin or oral anti-diabetic medications, and organ failure.

DIAGNOSES

Laboratory data showed elevated insulin and C-peptide levels. Therefore, insulinoma and IAS were suspected. Abdominal computed tomography and magnetic resonance imaging ruled out insulinoma, and MTZ-induced IAS was finally diagnosed.

INTERVENTIONS AND OUTCOMES

The hypoglycemia symptoms resolved after MTZ was switched to propylthiouracil, confirming the diagnosis of IAS.

LESSONS

This case emphasizes the significance of life-threatening MTZ-induced IAS. IAS should be suspected in patients who develop spontaneous hypoglycemia, especially in those with underlying Graves' disease receiving MTZ who present with hyperinsulinism.

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.

Thyroid Dysfunction and Dysmetabolic Syndrome: The Need for Enhanced Thyrovigilance Strategies

Thyroid dysfunction (TD) is common in metabolic disorders such as diabetes mellitus (DM), cardiovascular disease (CVD), obesity, dyslipidemia, hyperuricemia, kidney and liver dysfunctions, and polycystic ovary syndrome (PCOS). Subclinical hypothyroidism (SHypo) worsens glycemic control in patients with DM, and these patients, especially those with Type-1DM, have higher prevalence of TD. Both TD and DM increase CVD risk. Even minor alteration in thyroid hormone (TH) levels can alter cardiovascular function. While hyperthyroidism increases systolic blood pressure and leads to high-output heart failure, hypothyroidism increases diastolic blood pressure and leads to low-output heart failure. Chronic subclinical hyperthyroidism (SHyper) and SHypo both increase the risk of hypertension, coronary artery disease (CAD) events, CAD deaths, and total deaths. SHyper alters cardiac morphology and function. SHypo causes dyslipidemia and endothelial dysfunction and increases the risk for weight gain and obesity. Overweight and obese patients often have hyperleptinemia, which increases the secretion of thyroid stimulating hormone (TSH) and induces TD. Dyslipidemia associated with TD can increase serum uric acid levels. Hyperuricemia promotes inflammation and may increase the risk for dyslipidemia, atherosclerosis, and CVD. TD increases the risk for developing chronic kidney disease. In nephrotic syndrome, proteinuria is associated with urinary loss of TH leading to TD. Some correlation between TD and severity of liver disease is also seen. TD and PCOS have common risk factors and pathophysiological abnormalities. Hypothyroidism must be excluded before diagnosing PCOS. Current guidelines do not strongly recommend thyroid screening in the presence of all metabolic disorders. However, pragmatic thyrovigilance is required. Clinicians must stay alert to signs and symptoms of TD, maintain high clinical suspicion, and investigate thoroughly. Drug-induced TD should be considered when TH levels do not match clinical findings or when patients are on medications that can alter thyroid function.

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 induced by exogenous insulin injection: a four-case series

BACKGROUND

Insulin autoimmune syndrome (IAS) is a rare cause of hypoglycemia and is characterized by the presence of insulin autoantibodies. Patients with IAS usually complain of hypoglycemia without any previous insulin received. Glucocorticoids and immunosuppressants are used to treat IAS.

CASE PRESENTATION

We report four patients with diabetes who were diagnosed with non-classical IAS and describe the treatment of these patients. Moreover, the differential diagnosis with hyperinsulinism is discussed.

CONCLUSION

High levels of insulin autoantibodies, as well as hyperinsulinemic hypoglycemia, are found in patients with diabetes mellitus and prior exogenous insulin exposure. This situation that we classified as non-classical IAS should be attached importance to.

Insulin Autoantibody Syndrome: Varying Clinical Presentations and Response Patterns of an Underrecognized Entity

CONTEXT

Insulin autoantibody syndrome (IAAS) is considered to be a rare cause of hyperinsulinaemic hypoglycaemia. Lack of familiarity with the varied clinical manifestations leads to underdiagnosis. Localization techniques aimed at insulin-secreting neoplasms and nesidioblastosis, which are expensive often are ordered when the correct diagnosis is not made.

AIMS

We describe the myriad of clinical manifestations associated with IAAS based on single centre experience.

SETTINGS AND DESIGN

Retrospective analysis of patients who got admitted with symptoms suggestive of hypoglycaemia and underwent mixed meal test and prolonged hypoglycaemic test from 2016 to 2019.

SUBJECTS AND METHODS

Retrospective data of 12 patients with IAAS who were diagnosed in the threeyear time period between 2016 and 2019 are included in this analysis. Clinical details, biochemical parameters and imaging modalities were analysed.

STATISTICAL ANALYSIS

All analyses were performed with SPSS software (version 17).

RESULTS

Total of twelve patients 12 (5 male and 7 females) were identified as IAAS. Median age of presentation was 57 years. Median insulin levels and median C-peptide levels were 300 miu/ml and 18.5 ng/ml respectively. Only 3 (25%) patients had spontaneous resolution. Steroid induced remission occurred by 3 months in the remaining patients. Intermittent hyperglycaemia was seen in 9 (75%) patients. Implicatable drug use preceding the occurrence of the clinical symptoms was observed in five patients.

CONCLUSION

IAAS is not uncommon in India. The diagnosis should be pursued in patients with hyperinsulinaemic hypoglycaemia especially when insulin levels are very high or when there is intermittent hyperglycaemia.

Insulin Autoimmune Syndrome: a rare case of hypoglycaemia resolving with immunosuppression

We report a case of a 58-year-old male presenting with confusion and hypoglycaemia. There had been no prior exposure to oral hypoglycaemic agents or insulin. He was found to have inappropriate endogenous hyperinsulinaemia. Insulinoma was excluded by detailed endocrine assessment. Insulin antibodies were positive in keeping with a diagnosis of insulin autoimmune syndrome (IAS). He was treated with prednisolone 5mg once daily and nutritional supplements leading to resolution of acute confusion and hypoglycaemic episodes. The patient also had severe psoriasis and following discharge was treated with a variety of immunosuppressant therapies. This was associated with disappearance of insulin antibodies after twelve months of follow up. While it is possible that there was spontaneous resolution of insulin antibodies, we speculate that his prednisolone and immunosuppressant therapy may have suppressed insulin antibody production. There are several well recognised associations with IAS and autoimmune conditions, including Grave's disease, systemic lupus erythematous and rheumatoid arthritis. To our knowledge this is the first reported case of insulin autoimmune syndrome, resolving with immunosuppressant treatment of psoriasis.