Background <p>Non-ketotic hyperglycemia is a clinical syndrome caused by poor blood glucose control, which can lead to unilateral chorea, seizures, headaches, and other neurological deficit symptoms. Due to the lack of specificity of clinical symptoms and unclear pathogenesis, many patients are misdiagnosed and may delay treatment.</p> Case presentation <p>Two male patients of Han nationality in China, one 61 years old and the other 33 years old, were admitted to our hospital with persistent hemianopia and headache, both with a background of type 2 diabetes mellitus and poor glycemic control on admission. They also had abnormal signals on magnetic resonance imaging of the head, manifested as focal subcortical hypointensity and cerebral gyrus hyperintensity. Through comprehensive evaluation of clinical features, imaging changes, and treatment effect, the diagnosis of non-ketotic hyperglycemia was considered to be relatively clear. After active diagnosis and treatment, reasonable control of blood glucose, clinical symptoms, and abnormal imaging changes disappeared completely. No evidence of recurrence was found in patients with follow-up for half a year.</p> Conclusion <p>Clinicians should improve the necessity of non-ketotic hyperglycemia screening for patients with sudden headache, visual field defect, epilepsy, and hemichorea. This case report emphasizes the clinical diagnosis and treatment ideas and measures of non-ketotic hyperglycemia to increase the sensitivity of clinical diagnosis and the clinical detection rate.</p>