[PMC free article] [PubMed] [Google Scholar]. titers of insulin receptor antibodies despite a typical clinical course and response. Future research is needed to improve diagnosis and treatment in this rare disease. Keywords: hypoglycemia, insulin receptor antibodies, insulin resistance, type B insulin resistance A patient with type B insulin resistance who presented with severe hypoglycemia had a good response to immunosuppressive therapy and intravenous immunoglobulins. Type B insulin resistance is a rare syndrome caused by autoantibodies to the cell surface insulin receptor [1]. This heterogenous metabolic syndrome is seen predominantly in African American women in the United States [2]. It almost always occurs concomitantly with an underlying autoimmune systemic disease such as systemic lupus erythematosus (SLE). It causes a spectrum of abnormalities ranging from severe hyperglycemia with extreme insulin resistance to intractable hypoglycemia. Other associated features are hyperandrogenism and acanthosis nigricans [3]. The exact prevalence and disease course are not well known because of the rarity of this syndrome. High-dose steroids, immunosuppressants (such as cyclophosphamide), cyclosporine A, azathioprine, rituximab, and plasmapheresis have been used in treatment, with variable effects [4C6]. We describe a patient whose clinical presentation and phenotype were consistent with type B insulin resistance and who responded to empiric TNFRSF9 treatment before the diagnosis could be completely established. This case demonstrates the difficulty in diagnosing and treating this condition. 1. Case Report A 60-year-old African American woman with a history of SLE and Hashimoto WS3 hypothyroidism presented with substantial weight loss, nausea, and vomiting. She also noted frequent episodes of hypoglycemia over the preceding 3 months. She reported that her hypoglycemia could occur both overnight and a few hours after a meal. She had noticed dramatic weight loss of almost 100 pounds over a 12-month period. Physical examination revealed acanthosis nigricans on the face, neck, and upper back. She did not report any symptoms of hyperandrogenism. One year earlier, the patient was hospitalized for comparable episodes of symptomatic and refractory hypoglycemia, with serum WS3 glucose values as low as 37 mg/dL. Investigations at that time indicated a hyperinsulinemic WS3 state (insulin, 661 IU/mL [normal range, 2 to 19.6 IU/mL]; proinsulin, 58.4 pmol/L [normal, <18.8 pmol/L]; C-peptide, 9.1 ng/mL [normal range, 0.8 to 3 ng/mL]; glycosylated hemoglobin, 7.3%) (Fig. 1 and ?and2)2) with blood glucose level of 49 mg/dL. A cosyntropin stimulation test yielded appropriate cortisol values of 9 g/dL, 20 g/dL, and 23 g/dL at baseline, 30 minutes, and 60 minutes, respectively. Results on sulfonylurea screen and testing for serum insulin growth factor 2 were unfavorable. Computed tomography of the stomach with contrast showed a normal pancreas with no masses. She responded to treatment with intravenous (IV) immunoglobulin for three cycles, along with prednisone, 60 mg daily. The plan was to taper the prednisone dose gradually, but this resulted in hyperglycemia. She was diagnosed with type 2 diabetes and sent home on a basal bolus insulin regimen. Open in a separate window Physique 1. Insulin pattern. Arrows indicate treatment. Open in a separate window Physique 2. HbA1c pattern. Arrows indicate treatment points. Because of the discrepancy in the proinsulin and insulin levels and her extensive history of autoimmune disorders, it was thought that she might have insulin receptor antibodies. Unfortunately, she was lost to follow-up and returned 1 year later. She did not have any hospitalizations elsewhere and had not seen another provider in the interim for this issue..
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