Hypoglycemia secondary to type B insulin resistance syndrome

Type B insulin resistance syndrome (TBIRS) is rare, with an unknown prevalence, characterized by antibodies directed against the insulin receptor. TBIRS may present with hypoglycemia and/or hyperglycemia. A case of hypoglycemia secondary to TBIRS is reported. A 24-year-old woman presented with hypoglycemia associated with the adrenergic and neuroglycopenic symptoms. Clinical examination was normal. After workup, including a 72-hour fast, glucagon test, autoimmune screen, computerized tomography of the abdomen and calcium stimulation test, no cause was apparent. The results of the 72-hour fast were equivocal. Given the lack of a diagnosis, antibodies to insulin receptors were measured and found to be positive, confirming TBIRS as the cause. Oral glucocorticoid therapy was initiated, and no further hypoglycemic episodes occurred. Steroid therapy resulted in iatrogenic Cushing syndrome. Steroid therapy was discontinued after 1 year of initiation. She delivered a healthy baby with no neonatal hypoglycemia. Hypoglycemic episodes recurred 3 years later, at which point she had relocated and was treated elsewhere. Although rare, autoimmune causes of hypoglycemia should be considered when other causes are excluded or when results are equivocal. Management with pharmacotherapy can be effective in inducing remission but long-term monitoring is necessary as patients may relapse.