To explore the value and clinical significance of glycosylated hemoglobin (HbA1c) in the assessment of neurological function in acute ischemic stroke patients. Methods: A total of 120 patients with acute ischemic stroke were recruited to the study and randomly divided according to serum HbA1c level at admission into the control group (HbA1c<6.5%) and elevated group (HbA1c≥6.5%) with 60 patients per group. General information was compared between the two groups. After 2 weeks of treatment, cognitive function in the two groups was measured using the Montreal Cognitive Assessment (MoCA). Head CT scan was performed on day 3 of admission to assess cerebral infarction volume and location. The degree of neurological dysfunction was assessed by the National Institutes of Health Stroke Scale (NIHSS) at week 5 of treatment. Prognosis was graded using the scale for clinical neurological deficit of stroke patients after 5 weeks of treatment. Results: The proportion of patients with diabetes in the elevated group was significantly higher than that in the control group (P<0.01). The total MoCA score and all subscores of the elevated group were significantly lower than those of the control group (P<0.05). Patients with larger cerebral infarction volumes showed higher levels of HbA1c than those with smaller cerebral infarction volumes (P<0.05). The NIHSS score in the elevated group was significantly higher than that in the control group, and the neurological deficit was also more severe than that in the control group (both P<0.05). The prognosis of the elevated group was significantly worse than that of the control group (P<0.05). Conclusion: Glycated hemoglobin is closely related to the severity of neurological impairment and to prognosis in AIS patients.