ObjectiveTo explore the association between prediabetes and poor outcome in patients with acute ischemic stroke (AIS).MethodsThe patients with first-ever AIS who were hospitalized in the Department of Neurology, the First Affiliated Hospital of Henan University of Science and Technology from September to December 2018 were retrospectively enrolled. According to the different levels of hemoglobin A1c, the patients were divided into prediabetes group, diabetes mellitus (DM) group and non-DM group. The outcome of the patients 3 months after the discharge was assessed by the modified Rankin Scale and dichotomized as good and poor outcomes. ResultsA total of 188 patients were included, and 160 were eventually included. Among them, 66 cases were in the non-DM group, 39 were in the prediabetes group, and 55 were in the DM group; 68 patients were in the poor prognosis group and 92 were in the good prognosis group. There was no statistically significant difference among the non-DM group, prediabetes group, and DM group (P>0.05) except for hyperlipidemia (χ2=7.781, P=0.020), triglyceride (TG) (F=8.220, P<0.001) and admission blood glucose (F=44.356, P<0.001). There was no statistically significant difference between the good prognosis group and the poor prognosis group (P>0.05) except for hyperlipidemia (χ2=4.847, P=0.028), admission blood glucose (t=−2.940, P=0.004), TG (t=−2.766, P=0.006), and NIHSS (Z=−6.038, P<0.001). Prediabetic [odds ratio (OR)=4.053, 95% confidence interval (CI) (1.491, 11.019)] and diabetic [OR=5.986, 95%CI (2.330, 15.379)] patients had a worse prognosis 3 months after the discharge.ConclusionIn adults with first-ever AIS, prediabetes and diabetes were associated with poor prognosis in patients with AIS after 3 months.