Abstract
Immune checkpoint inhibitors (ICIs) have emerged as the cornerstone of treatment in a broad range of neoplasms, but at the cost of several types of immune-related adverse events (irAEs), some of which can also involve the endocrine system. Among those, ICI-induced diabetes mellitus (ICI-DM), while generally considered rare, has been growing in incidence in the past years. While this growth mostly reflects the expanding indications for the use of ICI, several other risk factors have also been described, but they have not been fully characterized. As with the majority of endocrine irAEs, once an endocrine loss of function occurs, it is usually irreversible and requires lifelong substitution therapy. However, the uniqueness of ICI-DM among those stems from the fact that its clinical presentation is usually acute, often life-threatening, and sometimes requires at least brief cessation of immunotherapy. In this paper, we report three cases of ICI-DM and provide a review of the literature regarding this topic, while presenting the real-world clinical lessons we learned from managing these cases, which can prove valuable for both oncologists and endocrinologists.