Objective: Hyperglycemia is associated with poor outcomes after acute stroke. A high incidence of patients who developed stroke may have hyperglycemia as high to 40%, even without a previous history of diabetes. Studied found that preexisting hyperglycemia and NIHSS ≥ 10 were predictors of worse stroke outcome. We considered if hyperglycemia associated with stroke severity. We aimed to assess whether non-diabetes stroke patients with and without hyperglycemia have presented a similar illness severity? worsens the clinical outcome of acute stroke. Methods: All patients with acute ischemic stroke (N = 3,135) admitted to a tertiary care, teaching, and referral hospital the south of Thailand, from October, 2011 to February, 2016, were reviewed. There were 2,336 non-diabetes and eligible data for analysis. Hyperglycemia was defined as fasting blood glucose > 120 mg/dL (> 6.7 mmol/L). Illness severity was assessed by using Glasgow Coma Scale (GCS), National Institutes of Health Stroke Scale (NIHSS), modified Rankin Scale (mRS), and Barthel Index (BI) on admission. Independent t-test, or Mann-Whitney test were used to compare illness severity scores. Results: Rate of hyperglycemia was 38%. Compared to non-hyperglycemia, strokes with hyperglycemia were more likely had lower scores on GCS (13.78 ± 2.36 vs 14.22 ± 1.77, t = 4.83, p = 0.000), and BI (65.37 ± 24.95 vs 70.79 ± 23.79, t = 5.18, p = 0.000). Higher scores of NIHSS (8.14 ± 6.95 vs 6.70 ± 5.94, t = 5.19, p = 0.000), and mRS (2.99 ± 5.24 vs 2.79 ± 6.31, z = 2.57, p = 0.010). Conclusion: This study provided convincing evidence that non-diabetic strokes with hyperglycemia had more clinical severity than non-hyperglycemia. Co-existing of hyperglycemia with clinical severely may counterparts worsen stroke outcomes.