7507 Early Detection of Hyperglycemia Using CGM Despite Reduced Dosing of Teprotumumab

Abstract Disclosure: L. Needleman: None. S.H. Kim: None. A.L. Kossler: None. C. Dosiou: None. Background: In a previous longitudinal observation study, we showed that patients with prediabetes increased HbA1c by a mean of 0.7% and 30% progressed to type 2 diabetes after treatment with teprotumumab for 3 months, or after 4 infusions [1]. However, temporal effects of hyperglycemia and the impact of lower doses of teprotumumab on hyperglycemia are unknown. Clinical case: An 86-year-old woman was diagnosed with Graves’ disease after evaluation for palpitations showed undetectable TSH, free T4 2.31 ng/dL (ref. 0.8-1.8 ng/dL), total T3 252 ng/dL (ref. 76-181 ng/dL), and elevated TSI (5.0, ref. <1.3). Thyroxine levels normalized four weeks after starting methimazole. Nine weeks after the initial presentation she developed diplopia and bilateral proptosis. She was diagnosed with active moderate-to-severe thyroid eye disease (CAS 4/7) and was started on teprotumumab 10 mg/kg intravenously every three weeks. The dose was not increased to 20 mg/kg due to concern for adverse effects given the patient’s age and underlying hearing impairment. At baseline, she had prediabetes based on a HbA1c of 6.0%. Additional risk factors for type 2 diabetes included older age and Asian race [1]. Continuous glucose monitoring (CGM, Dexcom G7) before starting teprotumumab showed 71% time in tight range (TITR, 70-140 mg/dL) with average fasting glucose of 115 mg/dL. Prior to starting teprotumumab, she received counseling for lifestyle modification including carbohydrate moderation. Ten days following her first teprotumumab dose, her TITR reduced to 66%. After three doses of teprotumumab, her proptosis improved by 2 mm, CAS decreased to 1/7, and diplopia resolved. However, the TITR was 59% and average fasting glucose increased to 128 mg/dL. HbA1c also increased to 7.4% and the patient was started on metformin. Conclusion: In this case, teprotumumab increased glucose as early as after the first infusion. Glucose tolerance continued to worsen with subsequent doses, with development of type 2 diabetes, even with reduced dosage of teprotumumab. This case demonstrates that monitoring for teprotumumab-related hyperglycemia can be optimized with use of CGM and that lower doses of teprotumumab do not eliminate the risk of worsening glucose tolerance. Whether hyperglycemia would have been more severe with full dose teprotumumab remains uncertain. Reference: [1] Amarikwa L, Mohamed A, Kim SH, Kossler AL, Dosiou C. Teprotumumab-Related Hyperglycemia. J Clin Endocrinol Metab. 2023 Mar 10;108(4):858-864. Presentation: 6/3/2024