Objective To investigate the correlation between blood glucose and stroke-associated infection (SAI) as well as the effect of accurate control over blood glucose on T-lymphocytes.Methods Stroke patients with stress hyperglycemia (random blood glucose ≥ 11.1 mmol/L) were divided into thc accurate control of blood glucose group (A) and the control group (C).The blood glucose was accurately controlled within 5.56-8.33 mmol/L in the group A and ＜ 11.10 mmol/L in the group C by infusion of regular insulin.The NIHSS and APACHE Ⅱ evaluation were performed at day 0,3 and 7 after admission,T-lymphocytes were measured by flow cytometry and the rate of stroke-associated infection was recorded.Results A total of 325 patients were enrolled in the present study.The patients in the group A had lower incidence of stroke-associated infection (51.8％ vs.64.0％,P =0.027) and lower incidence of hypoglycemia (2 vs.25,P ＜ 0.05).Lower level of average blood glucose [(7.00 ± 0.85) mmol/L vs.(8.97 ±1.68) mmoL/L,P ＜0.05] and lower blood sugar variability (12.1％ vs.18.7％,P ＜0.05) were found in the patients of group A compared with the group C.The patients in the group A at day 7 after admission showed higher counts of CD8 +,CD4 +and CD4 +/CD8 + [(0.42 ±0.13) × 109L-1vs.(0.34 ±0.12) ×109L-1,(0.50±0.13) ×109L-1vs.(0.39±0.17) ×109L-1and (1.36±0.14) vs.(1.14 ± 0.15) respectively,all P ＜ 0.05].Logistic regression analysis showed that blood glucose and CD4 + count were independent risk factors of stroke-associated infection.The AUCs of CD4 + and CD8 + for predicting stroke-associated infection were 0.814 and 0.724,respectively.The AUC (0.890) of a combination of CD4 + and CD8 + was significantly higher than that of CD4 + or CD8 + alone in predicting strokeassociated infection.Conclusions Accurate control over blood glucose decreases the fluctuation of the blood glucose level and the incidence of hypoglycemia.It improves the immunity associated with T lymphocyte,decreases the incidence of stroke-associated infection and thus improves prognosis of those patients.