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

INTRODUCTION: 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. METHODS: 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. RESULTS: 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. DISCUSSION: 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. CONCLUSION: 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.