A case of systemic lupus erythematosus in a patient with Noonan syndrome with recurrent severe hypoglycemia

Noonan syndrome (NS) is a dominantly inherited genetic disorder with mutations in genes encoding components or regulators of the RAS/mitogen-activated protein kinase pathway. Its diagnosis is based on characteristic features, including typical facial features, a short stature, congenital heart disease, mild developmental delay, and cryptorchidism. Patients with NS sometimes develop autoimmune diseases, such as Hashimoto's thyroiditis and, rarely, systemic lupus erythematosus (SLE). We herein present a 29-year-old Japanese female with NS complicated by SLE and repeated severe hypoglycemia. The patient was diagnosed with SLE based on thrombocytopenia, nephritis, a positive antinuclear antibody titer (1:640), and a positive anti-dsDNA antibody. The patient was treated with a glucocorticoid, mycophenolate mofetil, and tacrolimus, which attenuated both SLE and hypoglycemia. Since insulin receptor antibody levels were higher to the upper normal range and decreased after treatment, hypoglycemia probably appeared to be attributed to type B insulin resistance syndrome (TBIRS). We herein present the first case of SLE in NS complicated by TBIRS. Although NS is a rare disease, we need to consider the complication of autoimmune diseases, including SLE.

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.

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.

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.

Searching for the Culprit: When Diabetic Ketoacidosis Presents With Insulin Autoantibodies

Objective

The main objective was to describe and review a unique case that presented with diabetic ketoacidosis, positive insulin autoantibodies (IAAbs, which are found in Hirata disease and are usually present with hypoglycemia), and laboratory findings characteristic of type B insulin resistance syndrome (TBIRS) and systemic lupus erythematosus. Confirmation of TBIRS was obtained in Germany as immunoassay for insulin receptor antibodies (IRAbs) is not available in the United States.

Methods

A literature review on TBIRS and cases that present with IAAbs and IRAbs simultaneously was conducted.

Results

We found 6 cases presenting with hypoglycemia, both antibodies, and treatment attempts with various management approaches that were different from the proposed National Institutes of Health (NIH) protocol for TBIRS. Our case is distinct because of the demographic background, presentation with diabetic ketoacidosis, comparatively lower insulin requirement, and no significant hypoglycemic episodes in the third phase.

Conclusion

We propose that access to IRAb immunoassays may be important for diagnosing milder cases of TBIRS, while IAAbs may provide prognostic and therapeutic insights. Despite completely different presentation from other TBIRS patients reviewed, we observed that the proposed NIH protocol consisting of dexamethasone, rituximab, and cyclophosphamide was successfully employed in our patient. Thus, we propose that our case and the findings regarding antibody testing and the NIH treatment regimen may assist clinicians with earlier recognition and effective management of milder cases of TBIRS.

Saibokuto as a Possible Therapy for Type B Insulin Resistance Syndrome: The Disappearance of Anti-insulin Receptor Antibody and a Marked Amelioration of Glycemic Control by Saibokuto Treatment

Type B insulin resistance syndrome is a rare autoimmune disease and no effective therapy has yet been established. On the other hand, it is known that Saibokuto, one type of Japanese Kampo medicine, may have beneficial effects on various symptoms associated with this disease and it is therefore occasionally prescribed for various immune disorders. We herein describe a case of type B insulin resistance syndrome in which anti-insulin receptor antibody disappeared and the patient's glycemic control markedly improved after the administration of Saibokuto. At first, we administered various anti-oral diabetic drugs and insulin therapy, but the patient's glycemic control became further aggravated. In addition, Helicobacter pylori eradication therapy was not effective, although its benefit has been reported. Interestingly, after the patient started taking Saibokuto, her glycemic control markedly improved. In addition, the patient's plasma insulin levels markedly decreased and anti-insulin receptor antibody became negative after taking Saibokuto. Taken together, there is a possibility that Saibokuto may one of the options for type B insulin resistance syndrome therapy.