Objective: Trauma, due to stimulating stress responses like hormones, increases the blood sugar level (BS level). By inducing neurohormonal reactions, acute trauma leads to changes in carbohydrate, protein, and fat metabolism. As it was said, by releasing special cytokines and body defense regulating hormones, trauma results in increased BS level . This study aims to compare severity of injury (based on injury severity score classification) with BS level in traumatic patients. Methods: The retrospective study design and second data analysis from the patient’s health records were collected. A total of 266 traumatic patients who were admitted at tertiary hospital, South of Thailand during January 1, 2016 to December 31, 2016. Patients were selected according to the following criteria: age ≥ 15 years, no comorbidity of diabetes mellitus (DM) and first blood sugar test at emergency department. Patient were devided into three group from injury severity score (ISS): mild trauma (ISS 0-15), moderate (ISS 16-24) and severe (ISS 25-75). Results: Most of the patients in this study were men 78.6% (n = 209), an average age of 34.92 ± 15.53 years old, no comorbidity 97.7% (n = 260), blunt injury 75.6% (n = 201) and cause of injury was traffic accident 71.4% (n = 190). The mean of ISS was 13.03 ± 7.74 , mild trauma 63.2% (n = 168), moderate 26.7% (n = 71) and severe 10.2% (n = 27). The mean of BS level in patients was 146.66 ± 45.96, mild trauma group was 137.51 ± 40.05, moderate 155.45 ± 47.68 and severe 180.48 ± 56.25. Finally, we compared mean BS level of between group were differenced of statistical significant (p = .000). Conclusion: Severity of injury is a significant factor for high BS level. It is a result of the hypermetabolic response to stress and lead to complication in traumatic patients. Resuscitation and the management of life-threatening injuries as they were identified are essential to maximize patient survival. Recent recommendations support the principle of control BS in severe traumatic patients.