Type B Insulin Resistance: A Rare Type of Diabetes Mellitus

ABSTRACT Objective: Recognize the clinical and diagnostic features of diabetes caused by type B insulin resistance and treat with immunosuppressive therapy. Methods: A 27-year-old Asian male with a recent diagnosis of systemic lupus erythematosus (SLE) presented to his primary care physician complaining of a 2-month history of polydipsia, polyuria, unintentional 20-pound weight loss, and darkening of the skin on his posterior neck, back, and axilla. He had no family history of diabetes. The patient was presumed to have type 2 diabetes mellitus and started on oral medications. He continued to have poor glycemic control for 8 months despite treatment with multiple oral hypoglycemic agents (metformin, pioglitazone, sulfonylurea), glucagon-like peptide-1 agonist, and high doses of insulin. Given the history of SLE, hypercatabolic state, and severe acanthosis nigricans on examination, type B insulin resistance was suspected. The diagnosis was confirmed by the presence of high titer of insulin receptor antibodies. The patient was treated with rituximab, cyclophosphamide, and pulse dose steroids per National Institutes of Health protocol. Results: Four months after treatment the glycemic control improved and after 7 months the patient's diabetes went into remission and all the metabolic derangements resolved. Conclusion: Type B insulin resistance is an autoimmune disorder caused by autoantibodies against the insulin receptor. Recognition of this syndrome remains important, because it affects both treatment and prognosis. Our patient responded well to the immunosuppressive regimen with remission of his severe insulin resistance and resolution of the metabolic abnormalities. Abbreviations: AN = acanthosis nigricans ANA = antinuclear antibody NIH = national Institutes of Health SLE = systemic lupus erythematosus