Rare case of type B insulin resistance in association with systemic lupus erythematosus: illustrating diagnostic and management challenges.

A 42 year-old Caribbean woman with, known type 2 diabetes, was admitted with worsening fatigue, arthritis and rashes. She was diagnosed with multisystem systemic lupus erythematosus and was initially treated with systemic steroids. During this admission, she had persistently elevated capillary glucose levels with insulin requirements over 8 U/kg/day that still did not control her blood glucose levels. Due to her profound hyperglycaemia, serum samples of fasting insulin, C-peptide, paired with blood glucose were analysed, which confirmed significant hyperinsulinaemia. Further analysis confirmed the presence of insulin receptor antibodies consistent with type B insulin resistance.She was started on intravenous cyclophosphamide (Euro-Lupus regimen) along with continuous glucose monitoring system. After completing her six cycles of cyclophosphamide, she no longer required insulin treatment. The goal of therapy for our patient with confirmed type B insulin resistance was to manage hyperglycaemia with high doses of insulin until autoantibodies were eliminated with immunosuppressive therapy.