Long-Term Follow-Up of a Case of Severe Hyperglycemia Requiring Hospitalization after Third Dose of Teprotumumab: A Case Report.

Introduction: In 2020, teprotumumab became the first FDA-approved treatment for thyroid eye disease (TED). In clinical trials, hyperglycemia had been described as mild and controlled with medication. We present a case that occurred in 2020 of a 67-year-old male with TED and pre-existing glucose intolerance, who was hospitalized with severe hyperglycemia (1,059 mg/dL) after three doses of teprotumumab.

Case presentation: This patient's HbA1c was in the pre-diabetic range (6.3%) 6 months prior to initiating teprotumumab. After three doses, the patient was hospitalized with hyperosmolar hyperglycemic nonketotic syndrome and an HbA1c of 11.7%. He was diagnosed with type 2 diabetes mellitus and treated with insulin aspart mixed 70/30. He remained on this regimen for 14 months with an A1c of 6.0%. He then self-discontinued the insulin, with an A1c 4 months later measuring 5.5%. The patient's latest HbA1c approximately two and a half years after hospitalization was 6.1% on no medications.

Conclusion: It appears that teprotumumab was a trigger for this transient case of diabetes, and detecting those that have underlying glucose intolerance ahead of time is important. We recommend blood glucose levels for patients with pre-diabetes prior to and ideally in the first few days after each infusion, to help determine patients at a greater risk for adverse hyperglycemic outcomes. A glucometer may be valuable for patients to self-monitor while on teprotumumab. If fasting blood glucose is ≥126 mg/dL or non-fasting glucose is >200 mg/dL, patients should be referred for further diabetes assessment and possible treatment initiation.