Preventing Life-Threatening Hyperglycemia in Immune Checkpoint Inhibitor-Induced Type 1 Diabetes: Insights From Two Cases and Literature Review

In recent years, the use of immune checkpoint inhibitors (ICIs) has expanded rapidly, accompanied by a marked increase in associated immune-related adverse events (irAEs). Among these, ICI-related type 1 diabetes (ICI-T1D) is frequently recognized only after the onset of life-threatening hyperglycemia, in part due to its rare prevalence and latent nature of disease progression. Herein we report two cases of ICI-T1D successfully treated before the development of marked hyperglycemia. In both cases, despite the complete depletion of insulin secretion, blood glucose control was achieved prior to the onset of diabetic ketoacidosis, and the clinical course could be monitored in detail, making them valuable cases for documentation. Taken together with the literature, these cases suggest that, compared with classic fulminant type 1 diabetes (FT1D), ICI-T1D tends to progress more gradually. Even in the presence of only mild hyperglycemia and partially preserved insulin secretion, its onset should be suspected and the clinical course monitored carefully. Since most patients undergo regular blood testing, careful monitoring may allow for the timely detection and optimal management of ICI-T1D. In addition, we found that not only glucose metrics but also transient increases in red cell distribution width (RDW) levels may be a new predictive marker for irAEs.