Successful treatment of type B insulin resistance with mixed connective tissue disease by pulse glucocorticoids and cyclophosphamide

Type B insulin resistance syndrome is a very rare condition caused by autoantibodies against the insulin receptor. We report the successful treatment of a patient with refractory type B insulin resistance with pulse glucocorticoids and cyclophosphamide. The medical record of a patient with type B insulin resistance was reviewed. A 36-year-old Chinese woman presented with menopause, weight loss and refractory hyperglycemia for 3 months, which could not be controlled by up to 972 of insulin units per day. Mixed connective tissue disease was diagnosed with high titers of antinuclear antibody, ribonucleoprotein antibody and interstitial lung disease. Type B insulin resistance was diagnosed with positive immunoprecipitation assay of anti-insulin-receptor antibodies in serum. We started one cycle of pulse methylprednisolone (1,000 mg/day for 3 days) then tapered to prednisone 1 mg/kg/day, and cyclophosphamide 0.4 g/week was added on. Three weeks after pulse glucocorticoid therapy, fasting glucose returned to 4.4 mmol/L. Fasting insulin decreased from 647.27 to 12.95 uIU/mL 6 weeks later. The patient had gained 15 kg during 20 months of uneventful following up, and glycated hemoglobin decreased from 10.1 to 5.1%.In this patient with type B insulin resistance, a combination of pulse glucocorticoids and cyclophosphamide was successful in inducing a complete remission. Close cooperation between endocrinologists and rheumatologists will ensure an individualized regimen for this rare condition.