SAT-033 - Metabolic Clues to Acromegaly: A Case of Severe Insulin Resistance

Background: Acromegaly is a rare endocrine disorder with an estimated prevalence of approximately 0.004–0.007% of the population and an annual incidence of 0.0003–0.0004%. Excess growth hormone and insulin-like growth factor-1 lead to significant metabolic complications, with impaired glucose tolerance reported in up to 30–50% of affected patients. Population-based studies demonstrate prolonged diagnostic delays, often exceeding 5–10 years from symptom onset. Social barriers may further hinder recognition and treatment.

Case Presentation: A 63-year-old man with insulin-dependent diabetes mellitus, chronic obstructive pulmonary disease, and newly diagnosed moderately differentiated invasive carcinoma of the right lung was admitted with shortness of breath and treated for post-obstructive pneumonia. His hospital course was notable for persistent hyperglycemia refractory to escalating insulin therapy, which prompted endocrine consultation. Physical examination revealed features suggestive of acromegaly, prompting further laboratory evaluation, which demonstrated markedly elevated insulin-like growth hormone levels (809 ng/mL). As a part of cancer screening, MRI revealed no metastatic disease but demonstrated an enlarged pituitary gland, prompting further laboratory evaluation, with low free T4 0.644 ng/dL, normal TSH 0.899 µIU/mL, elevated prolactin 79.9 ng/mL, gonadotropins LH 2.2 mIU/mL, FSH 11.5 mIU/mL, morning cortisol of 9.3 µg/dL. A working diagnosis of acromegaly was established. The patient was started on bromocriptine 2.5 mg daily, with subsequent improvement in prolactin levels to 55.8 ng/mL; the dose was titrated to 7.5 mg orally daily. Levothyroxine 75 mcg daily was initiated for central hypothyroidism, with follow-up free T4 improving to 0.929 ng/dL. Glycemic control remained challenging, requiring high doses of insulin. The patient was discharged on insulin glargine 95 units twice daily, insulin lispro 40 units three times daily before meals with sliding-scale coverage, bromocriptine 7.5 mg daily, and levothyroxine 75 mcg daily for central hypothyroidism, with plans for outpatient endocrinology follow-up and further treatment including somatostatin analogues/surgery. The patient was uninsured and residing in a shelter, creating significant barriers to medical care, including oncologic treatment and glucose management.

Conclusion: Severe, refractory hyperglycemia may serve as an important metabolic clue to underlying acromegaly. Careful physical examination remains critical for early recognition, particularly in patients with complex comorbidities and limited access to care, where timely diagnosis may significantly impact endocrine and metabolic outcomes.

*Unless otherwise noted, all abstracts presented at ENDO must not be released to the press or the public until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.*