Background and Purpose-Hemoglobin A1c (HbA1c) was recommended to diagnose diabetes mellitus, but whether newly diagnosed diabetes mellitus (NDDM) according to the new criteria was associated with stroke prognosis was unclear. We aimed to investigate the prognosis of ischemic stroke with NDDM according to the new criteria. Methods-Ischemic stroke without a diabetes mellitus history in the survey on Abnormal Glucose Regulation in Patients With Acute Stroke Across China were included in the analysis. NDDM was defined as fasting plasma glucose >= 7.0 mmol/L, 2-hour oral glucose tolerance test >= 11.1 mmol/L, or HbA1c >= 6.5%, and NDDM was divided into group 1, diagnosed by glucose criteria (fasting plasma glucose >= 7.0 mmol/L or 2-hour oral glucose tolerance test >= 11.1 mmol/L with/without HbA1c >= 6.5%), or group 2, diagnosed by single high HbA1c (fasting plasma glucose <7.0 mmol/L, 2-hour oral glucose tolerance test <11.1 mmol/L, and HbA1c >= 6.5%). The association between NDDM and 1-year prognosis (mortality, stroke recurrence, and poor functional outcome [modified Rankin scale score 3-6]) was estimated. Results-Among 1251 ischemic stroke patients, 539 were NDDM and 141 of NDDM with single high HbA1c. NDDM was an independent risk factor for 1-year mortality (hazard ratio, 1.12; 95% confidence interval, 1.001-1.26), stroke recurrence (hazard ratio, 1.14; 95% confidence interval, 1.01-1.28), and poor functional outcome (odds ratio, 2.58; 95% confidence interval, 1.95-3.43) compared with non-diabetes mellitus. Nevertheless, NDDM with single high HbA1c was not significantly associated with 1-year prognosis for all end points (P>0.05 for all). Conclusions-NDDM by new criteria was associated with poor prognosis at 1 year after ischemic stroke; however, NDDM with single high HbA1c did not predict a poor prognosis.