Case Report: Diabetic ketoacidosis in a patient with Klinefelter syndrome: a rare and complex presentation.

Background: Klinefelter syndrome (KS) is a sex chromosome abnormality disease, with a reported incidence of 0.1%-0.2%, while the prevalence of KS in male infertility patients is about 3.1%. Patients with KS are prone to experience metabolic abnormalities over time, such as obesity, diabetes, and metabolic syndrome, along with sexual dysfunction. Case presentation: This report describes a case in which diabetic ketoacidosis (DKA) developed in an individual with KS. Specifically, the case report concerns a 29-year-old male who presented to our hospital with a 3-day history of headache and poor appetite accompanied by a half-day of nausea and vomiting. After excluding issues with the patient's digestive system, DKA was suspected, and the patient was admitted to the hospital. Upon abdominal CT, it was noted by chance that the patient had small testicles and a small penis, and an interview with the patient and their family revealed that he had previously been diagnosed with Kallmann syndrome. After extra examination, including chromosome examination, it was revealed that the patient had an extra X chromosome (47, XXY), and Klinefelter syndrome was diagnosed. Conclusion: This case report provides case experience that can improve physicians' understanding of Klinefelter syndrome, including the differential diagnosis and treatment of the disease and its further progression, as well as the emergence and treatment of other diseases that may occur in subsequent developments and changes in such patients.