PMON101 Fluctuating Insulin Requirements in Untreated Acromegaly: From 200-to-0

INTRODUCTION: Acromegaly is a clinical disorder that occurs from autonomous production of growth hormone (GH). Diabetic ketoacidosis (DKA) is an uncommon and late complication of acromegaly. Acromegaly presenting in DKA prognosticates glycemic management with insulin-based regimens. Cessation of insulin therapy, however, can be achieved in patients with acromegaly after proper medical and/or surgical interventions. Our case highlights a unique outcome in a patient with newly-diagnosed acromegaly that initially presented in DKA with very high insulin requirements and was ultimately de-escalated off all anti-hyperglycemic therapy with significant glycemic improvement prior to any treatment for acromegaly. CLINICAL CASE: A 32 year-old male with a past medical history of colorectal cancer and no known history of diabetes presented to the emergency department for evaluation of generalized weakness, epigastric pain, nausea, and vomiting and was admitted for DKA. Hemoglobin A1c was 11.6% (reference range < 5.7%), confirming the diagnosis of newly-diagnosed diabetes. C-peptide was 1.4 ng/mL (reference range 0.5-3.3 ng/mL) and anti-glutamic acid decarboxylase, anti-islet cell, and anti-zinc transporter 8 antibodies were all negative. He was initiated on intravenous insulin infusion, with rates achieving > 200 units of insulin per day. Given severe insulin resistance in conjunction with acromegalic features on physical exam and a unique history of colorectal cancer at a young age without any family history, evaluation for acromegaly was initiated. Human GH level was 68.60 ng/mL (reference range 0.05-3.00 ng/mL) and insulin-like growth factor-1 (IGF-1) level was 1,036 ng/mL (reference range 82-242 ng/mL). MRI brain revealed a hypoenhancing 1.3 cm lesion enlarging the left lateral pituitary gland. Diagnosis of acromegaly due to a GH-secreting macroadenoma was established. The patient was discharged on a high-dose insulin regimen in addition to metformin therapy with de-escalation off of all anti-glycemic therapy within a few weeks of diagnosis; at his 3 month follow-up visit, his repeat hemoglobin A1c was 6.1 with repeat GH level of 28.8 ng/mL and IGF-1 level of 1602 ng/mL, despite not yet undergoing any treatment for the underlying condition. CONCLUSION: DKA as an initial presentation of acromegaly has been previously reported in literature, however, not with a concomitant history of colon cancer. Moreover, no previous cases of acromegaly have reported glycemic normalization off of anti-hyperglycemic therapy prior to any treatment for acromegaly. Our case highlights that evaluation for secondary causes, including acromegaly, should be considered in patients with severe insulin resistance and emphasizes the dramatic range of insulin requirements that patients with acromegaly may have. Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.