Severe Hyperglycemia with Teprotumumab for Treatment of Thyroid Eye Disease.

Introduction: Thyroid eye disease (TED) is a rare condition involving autoimmune-mediated inflammation of the orbit and periocular structures, which can result in many debilitating symptoms. Teprotumumab, a monoclonal antibody that targets the insulin-like growth factor 1 receptor, is gaining popularity for the treatment of TED. In fact, owing to its efficacy and side effect profile, some recommend that it be considered as a first-line therapy for patients with TED. While teprotumumab is often chosen due to its efficacy and relatively favorable side effect profile compared to other treatments, there is a known risk of hyperglycemia with this mechanism of action, which is well described through clinical trials in the oncology literature. Though all cases in the clinical trial study of teprotumumab were mild, there is growing evidence that its effect on blood sugar can be more profound. Case Presentation: We present a case of a well-controlled, recently diagnosed type 2 diabetic placed on teprotumumab for treatment of TED who developed life-threatening hyperglycemia. The case report provides evidence of hyperglycemic risk, as it highlights a patient's significant increase in hemoglobin A1C to 15.4 in addition to elevated serum glucose of 954 mg/dL while receiving teprotumumab. Conclusion: This case of severe hyperglycemia accentuates the need for more diligent, if not universal, glucose monitoring during teprotumumab treatment.