Objective To continuously monitor the glucose level during the early phase of acute ischemic stroke (AIS) in patients without diabetes mellitus history, so as to provide evidences for detailed blood glucose information and prognostic evaluation. Methods Ninety-one consecutive non-diabetic AIS patients received continuous glucose monitoring and were divided into normoglycemia (n=20), transient hyperglycemia (n=31), and persistent hyperglycemia (n=40) groups. The general data, blood glucose fluctuation parameters and biochemical indices were compared between the three groups. The National Institutes of Health (NIH) Stroke Scale (NIHSS) scores were also compared between the three groups at 24 h, 7 d, and 14 d after treatment. Results The ratio of male patients and the ratio of cerebral infarction history and hypertension history in the persistent hyperglycemia group were significantly lower than those in the other two groups (P<0.05). Compared with the other two groups, the persistent hyperglycemia group had significantly higher mean blood glucose, standard deviation of blood glucose, largest amplitude of glycemia excursion, mean amplitude of glycemia excursion, and absolute mean of daily differences (all P<0.01). The levels of total cholesterol, triglyceride, low-density lipoprotein cholesterol, HbA_1c, C reactive protein, and homocysteine in the persistent hyperglycemia group were significantly higher than those in the other two groups (P<0.01). The NIHSS scores of the persistent hyperglycemia group were significantly higher than those of other groups at 7 d and 14 d after treatment (P<0.05,P<0.01). Conclusion Continuous glucose monitoring can accurately reveal the blood glucose metabolism during the early phase of AIS, contributing the following treatment and prognosis prediction.