Pasireotide in an insulin-requiring diabetic acromegalic patient without worsening of hyperglycemia

Abstract

Long-acting pasireotide is an effective treatment option for acromegaly, but it is associated with hyperglycemia, which could impact its use in patients with diabetes. We present a case of a 53-year-old man with acromegaly and type 2 diabetes mellitus (glycated hemoglobin (HbA1c): 7.5%), who refused surgery to remove a pituitary macroadenoma and enrolled in a Phase 3 clinical trial comparing long-acting pasireotide and long-acting octreotide in acromegalic patients. The patient initially received octreotide, but insulin-like growth factor 1 (IGF-1) levels remained elevated after 12 months (383.9 ng/mL; 193.0 ng/mL; reference range: 86.5–223.8 ng/mL), indicating uncontrolled acromegaly. He switched to pasireotide 40 mg and subsequently increased to 60 mg. Within 6 months, IGF-1 levels normalized (193.0 ng/mL), and they were mostly normal for the next 62 months of treatment with pasireotide (median IGF-1: 190.7 ng/mL). Additionally, HbA1c levels remained similar to or lower than baseline levels (range, 6.7% to 7.8%) during treatment with pasireotide despite major changes to the patient’s antidiabetic regimen, which included insulin and metformin. Uncontrolled acromegaly can result in hyperglycemia due to an increase in insulin resistance. Despite having insulin-requiring type 2 diabetes, the patient presented here did not experience a long-term increase in HbA1c levels upon initiating pasireotide, likely because long-term control of acromegaly resulted in increased insulin sensitivity. This case highlights the utility of long-acting pasireotide to treat acromegaly in patients whose levels were uncontrolled after long-acting octreotide and who manage diabetes with insulin.