SHM Converge Scientific Abstract ePoster Gallery-Double Trouble: Immune Checkpoint Inhibitor-Induced Diabetes and Hyperthyroidism in a Lung Cancer Patient

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This case describes a 56-year-old man with stage IV small cell lung cancer treated with carboplatin, etoposide, and atezolizumab who developed two concurrent immune-related endocrine toxicities: new-onset diabetes mellitus presenting as diabetic ketoacidosis and hyperthyroidism.<br /><br />He presented with abdominal pain, nausea, vomiting, polydipsia, polyuria, and palpitations. Labs showed severe hyperglycemia (glucose 560), anion gap metabolic acidosis (anion gap 31, bicarbonate 13), ketonuria, and low C-peptide (0.16), consistent with immune checkpoint inhibitor-induced autoimmune diabetes. Thyroid testing showed marked thyrotoxicosis with suppressed TSH, elevated free T4 and T3, and negative TSI, suggesting ICI-associated hyperthyroidism. Infectious and imaging workup were unrevealing.<br /><br />He was admitted to the ICU for DKA, treated with IV fluids and insulin infusion, then transitioned to basal-bolus insulin with good control. Endocrinology started methimazole and propranolol for hyperthyroidism and tachycardia. Oncology delayed the next atezolizumab cycle and planned outpatient reassessment of cancer therapy. He was discharged on lifelong insulin with endocrine follow-up.<br /><br />The presentation highlights that immune checkpoint inhibitors, particularly PD-L1 inhibitors like atezolizumab, can cause rare but serious endocrine immune-related adverse events. ICI-induced diabetes often presents as DKA, is associated with low C-peptide from beta-cell destruction, and usually requires permanent insulin therapy. Hyperthyroidism is more common and may later progress to hypothyroidism. Early recognition and coordinated endocrinology-oncology management are essential for patient safety and cancer treatment planning.

Asset Subtitle

Mallorie Vest

Meta Tag

Author List Mallorie Vest

Category Clinical Vignettes

Concept Immune Checkpoint Inhibitor-Induced Diabetes

Concept Diabetic Ketoacidosis

Concept Endocrine Immune-Related Adverse Event

Concept Hyperthyroidism

Concept C-Peptide

Distinguished Non-Finalist

Presenter Organization Washington University School of Medicine

Presenting Author Mallorie Vest

Track Adult

Keywords

small cell lung cancer

atezolizumab

immune checkpoint inhibitor

diabetic ketoacidosis

immune-related diabetes

hyperthyroidism

low C-peptide

thyrotoxicosis

methimazole

endocrine adverse event

Immune Checkpoint Inhibitor-Induced Diabetes

Diabetic Ketoacidosis

Endocrine Immune-Related Adverse Event

Hyperthyroidism

C-Peptide