Abstract: Objective To investigate the effect of type 2 diabetes (T2DM) on prognosis in patients with acute brain infarction. Methods Clinical data about consecutive acute cerebral infarction patients who were hospitalized in department of neurology in General Hospital of Jinan Military Region were prospectively recruited from August 2010 to August 2014, including age, sex, National Institute of Health Stroke Scale (NIHSS) score, type of Oxfordshire Community Stroke Project (OCSP: total anterior circulation infarct, partial anterior circulation infart, posterior circulation infarct and lacunar infarct), serum creatinine, with or without T2DM, fasting blood glucose within 24 hours after admission were recorded. Patients were divided into two groups according to with or without T2DM. Recovery was assessed by modified Rankin Scale (mRS) at 180 days after stroke by telephone interview (mRS≤2 reflected good prognosis, and mRS＞2 reflected unfavorable prognosis). Multinominal logistic regression analysis was used for investigating the effect of T2DM on prognosis. Results Of the 1 138 patients, 417 patients had T2DM, among them 253 patients were male with average age of (63.40±11.26) years; 721 patients did not have T2DM, among them 460 patients were male with average age of (64.48±12.92) years. In patients without T2DM group, 484 cases had good prognosis with mRS≤2 and 237 cases had unfavorable prognosis with mRS＞2. However, in patients with T2DM group, 247 cases had good prognosis with mRS≤2 and 170 cases had unfavorable prognosis with mRS＞2. The unfavorable prognosis rate of patients with T2DM was significantly higher than patients without T2DM (40.77% vs 32.87%, χ²=7.700, P=0.006). Conclusion T2DM was an independent prognostic factor for long-term poor outcome (OR=1.997, 95% CI: 1.414-2.281, P=0.000).