Immune Checkpoint Inhibitor-induced Diabetes Mellitus: A Clinical Case Series

Immune checkpoint inhibitors (ICIs) are a revolutionary class of drugs for the treatment of various malignancies by harnessing the immune system to eliminate cancer cells. However, their antitumor efficacy is accompanied by a spectrum of immune-mediated adverse effects, including endocrine disorders. Among them, diabetes mellitus, though rare compared to thyroid dysfunction, is a serious complication due to its abrupt onset and high risk of life-threatening diabetic ketoacidosis.

This article presents several clinical cases of ICI-induced diabetes mellitus with an emphasis on the clinical presentation, biochemical assessment, and the importance of early recognition.

Each of the patients in this clinical case series was admitted to the hospital on an emergency basis with significant hyperglycaemia and ketonuria. Given the established insulin deficiency (low C-peptide levels), after stabilization with intravenous insulin and rehydration, they were switched to maintenance therapy with subcutaneous administration of basal and rapid-acting insulin.

The management of immune-mediated diabetes mellitus requires an individualized approach, considering the rapid progression to insulin dependence, the oncologic status of the patient, and the need for continuation of immunotherapy.

Early identification through regular glucose monitoring and rapid insulin initiation are crucial for effective management of ICI-induced diabetes mellitus. Comprehensive care requires close cooperation between oncology and endocrinology teams, individualized follow-up, and lifelong insulin therapy.