Tirzepatide for pasireotide-induced hyperglycemia in a GH/TSH-producing pituitary adenoma/PitNET: a case report and literature review.

Pasireotide, a somatostatin analog with high affinity for somatostatin receptor 5 (SSTR5), is frequently used to treat residual or recurrent pituitary adenomas, but it often induces hyperglycemia by suppressing glucagon-like peptide-1 (GLP-1) secretion. Although GLP-1 receptor agonists (GLP-1RAs) have been reported to be effective for pasireotide-induced hyperglycemia, no established treatment strategy currently exists. The present report describes the first documented use of once-weekly subcutaneous tirzepatide in a patient with pasireotide-induced hyperglycemia that remained inadequately controlled despite oral GLP-1RA therapy. A 48-year-old woman without a history of glucose intolerance was diagnosed with a GH/TSH-producing pituitary adenoma/PitNET. Transsphenoidal surgery was performed, followed by initiation of pasireotide for the residual tumor. Subsequently, the patient developed progressive hyperglycemia, with the hemoglobin A1c (HbA1c) level increasing from 6.5% to 7.7%. Oral sitagliptin and semaglutide were sequentially introduced; however, glycemic control remained suboptimal. Upon switching to once-weekly subcutaneous tirzepatide, the HbA1c level decreased markedly from 7.7% to 6.3%, along with an improvement in random blood glucose levels. In conclusion, once-weekly subcutaneous tirzepatide may be a therapeutic option for selected patients with pasireotide-induced hyperglycemia. However, further studies are needed to determine whether its effects differ from those of intensified GLP-1RA therapy.