Two Sisters with Graves' Disease and Similar Clinical Features who Tested Positive for Anti-insulin Antibodies after Thiamazole Treatment

Long-term follow-up after discharge witnesses a slow decline of insulin autoantibodies in patients with insulin autoimmune syndrome complicated with Grave's disease: a report of two cases

BACKGROUND

Insulin autoimmune syndrome (IAS) is a rare cause of hypoglycemia characterized by high levels of blood insulin autoantibodies. It has been documented that drugs containing sulfhydryl groups may result in IAS. In this study, we present two cases of IAS induced by methimazole, along with their corresponding treatments and a long-term follow-up after hospitalization.

CASE PRESENTATION

We report two patients with Grave's disease (GD), carrying the HLA-DRB1 04:06 genotype, who experienced hypoglycemic episodes after taking methimazole. Inpatient treatments helped return their blood glucose levels to normal. Although no recurrences of hypoglycemia were present in the two cases studied, insulin autoantibodies remained positive for the previous follow-up sessions, which turned negative only three years after discharge.

CONCLUSIONS

GD patients who carry the HLA-DRB1 04:06 genotype are prone to IAS if they take drugs containing sulfhydryl groups. It may take time for the elimination of insulin autoantibodies after the recovery from the hypoglycemic episode in IAS patients.

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.

Insulin autoimmune syndrome possibly caused by coenzyme Q10

A 52-year-old woman was transported for reduced consciousness. Her blood glucose was only 19 mg/dL, but her blood immunoreactive insulin and insulin antibody levels were high at 250 μU/mL and 50 U/mL, respectively. She had no history of insulin treatment, but she had been taking coenzyme Q10 supplements for three months. Her human leukocyte antigen serotype was DR4. After stopping coenzyme Q10, her hypoglycemia disappeared and immunoreactive insulin and insulin antibody levels normalized. Based on the above, she was diagnosed with insulin autoimmune syndrome caused by coenzyme Q10. It is necessary to be aware of the onset of insulin autoimmune syndrome due to coenzyme Q10. Its pathogenesis requires clarification.