Type B insulin resistance syndrome (TBIRS) is a very rare autoimmune condition with polyclonal autoantibodies directed against the insulin receptor, which results in severe and refractory hyperglycemia and high mortality. Described here is a patient who, within a few months after the onset of an autoimmune type 1 diabetes, increased her insulin requirements more than 20-fold, and despite this having a considerable difficulty maintaining her P-glucose < 40-60 mmol/L. On suspicion of TBIRS the patient was started on tapering glucocorticoids to overcome the autoimmune insulin receptor blockade, resulting in an immediate and dramatic effect. Within days insulin requirements decreased by 80-90 %, and the P-glucose stabilized around 7-8 mmol/L. The presence of antibodies to the insulin receptor was detected by immunoprecipitation and binding assays. After a 4-month remission on low maintenance dose prednisolone the patient relapsed, which required repeated plasmaphereses with temporarily remarkable effect. Mixed and transient results were seen with rituximab, mycophenolic acid and bortezomib but glycemic control has remained suboptimal. Lack of compliance and recurrent infections may have contributed to this.