Immune checkpoint inhibitors (ICIs) perturb T-cell regulatory pathways to enhance antitumor immunity. However, an increase reporting of ICI-associated diabetes is observed in adults. To our knowledge, no cases have been reported in the pediatric population. RESEARCH DESIGN AND METHODS We describe a pediatric case of ICI-associated type 1 diabetes in a 12-year-old Hispanic boy with Hodgkin lymphoma. The patient had a history of autologous hematopoietic stem cell transplantation and was treated with pembrolizumab after disease progression. RESULTS The patient was admitted for diabetic ketoacidosis after five cycles of pembrolizumab. The patient was discharged with daily insulin injections and has continued on exogenous insulin ever since. CONCLUSIONS The expanded ICI use may lead to more cases in pediatric patients as has been observed in adults. Considering the acute manifestation of diabetes and the added burden of lifelong insulin therapy, in particular for pediatric patients and their families, monitoring and education of ICI-associated diabetes in children is needed. Insulin-dependent diabetes associated with immune checkpoint inhibitors (ICIs) is a rare phenomenon but of high clinical significance due to its presentation as potentially life-threatening diabetic ketoacidosis (DKA). In the setting of advanced malignancies, ICI-associated diabetes may seem peripheral, but its chronicity, complications, and daily glucose monitoring and insulin injections drastically alter patients' quality of life and complicate cancer treatment. Moreover, the unprecedented level of interest in immunotherapy research will lead to more widespread use of ICIs and a subsequent increase in diabetes, as evidenced by recent data (1-3). One study reported 283 new cases during a 4-year period, with more than half reported in 2017 (1). The primary cancer types were melanoma (43%), lung (32%), and renal (10%), indicative of early ICI approvals in these tumors. While the nature of ICI-associated diabetes is better defined for melanoma, other malignancies, such as lymphoma, are rarely reported, making it difficult to assess patient characteristics in various types of cancer that are approved for ICI use, especially for hematologic malignancies.