Programmed death receptor 1 (PD-1) inhibitors are a type of immune checkpoint inhibitors (ICI), which are widely used in cancer therapy, but can easily trigger immune-related adverse events, among which fulminant type 1 diabetic ketoacidosis (DKA) is relatively rare. As of February 2025, a search was conducted on PubMed, and a total of 59 cases of fulminant type 1 diabetes ketoacidosis (DKA) induced by ICI with complete data were summarized, including 31 males and 28 females. The median age at onset was 61 years (range: 14-87 years), and the primary tumors were mainly melanoma (27.1%) and non-small cell lung cancer (18.6%). Among the therapeutic agents, PD-1 monoclonal antibodies account for the highest proportion (67.8%), with pembrolizumab (18 cases) and nivolumab (17 cases). This paper reports a case of fulminant type 1 diabetic ketoacidosis in a patient with malignant gastric antrum tumor after treatment with the PD-1 inhibitor tirelizumab. At present, it is believed that its pathogenesis may be related to abnormal activation of the immune system. Diagnosis is mainly based on clinical symptoms and signs, laboratory tests, and relevant medical history. For cancer patients receiving PD-1 inhibitor therapy, a rapid rise in blood glucose and the onset of DKA symptoms in the short term should raise a high level of concern for this condition after excluding other common causes of diabetes. In terms of treatment, timely fluid resuscitation, ketone clearance, short-term insulin therapy, and active symptomatic management are crucial. ICI-related diabetes is not an absolute contraindication for PD-1 inhibitor therapy. Once the patient's condition stabilizes, it can be continued under close monitoring. In this case, this patient was diagnosed timely and accurately. After insulin therapy, blood glucose was well controlled. PD-1 inhibitors could be continued under strict monitoring after discharge. This case report provides clinical experience, reminding clinicians that when using PD-1 inhibitors, in addition to monitoring thyroid and pituitary function, blood glucose fluctuations should be monitored simultaneously, and multidisciplinary collaboration should be emphasized to avoid serious consequences of acute complications of diabetes.