Background: The association of prediabetes and outcome of patients with ischemic stroke or transient ischemic attack (TIA) remains controversial. We performed a systematic review and meta-analysis to assess the association between prediabetes and outcome of ischemic stroke or TIA. Methods: We comprehensively searched the PubMed and Excerpt Medica Database (EMBASE) from their inceptions to August 25, 2017. Studies that reported outcomes of patients with ischemic stroke or TIA and with information on prediabetic states at baseline were included. The end points were new stroke, mortality, and poor outcome (modified Rankin Scale score of 3-6 or 2-6). Results: A total of 8 studies with 10,975 patients with ischemic stroke or TIA were included in this meta-analysis, among which 4 studies reported the endpoint of new stroke, 5 studies reported mortality, and 6 studies reported poor outcome. Prediabetes was at increased risk of stroke compared with normal glucose metabolism (hazard ratio [HR]: 1.42, 95% confidence interval [CI]: 1.13-1.80; P = .003). Poor outcome was also more frequent in patients with prediabetes compared with normal glucose metabolism (odds ratio: 1.33, 95% CI: 1.11-1.59; P = .002), while mortality was not significant (HR: 1.69, 95% CI: 0.84-3.40; P = .14). There was no evidence of statistical heterogeneity among the included studies for stroke and poor outcome, but for mortality. Conclusions: Prediabetes was associated with an increased risk of new stroke and poor outcome, compared with normal glucose metabolism among patients with ischemic stroke or TIA.