Background and Aim: Although large studies have demonstrated the association between hyperglycemia and adverse intensive care unit (ICU) outcomes, it is yet unclear which subset of patients benefit from tight sugar control in ICU. Recent evidence suggests that stress induced hyperglycemia (SIH) and co-incidentally detected diabetes mellitus are different phenomena with different prognoses. Differentiating SIH from diabetic hyperglycemia is challenging in ICU settings. We followed a cohort of trauma patients admitted to a surgical intensive care unit (SICU) to evaluate if initial glycated hemoglobin A (HbA ₁ c) level predicts the outcome of admission. Materials and Methods: A cohort of 120 consecutive admissions to SICU following trauma were recruited and admission blood sugar and HbA ₁ c were measured. Outcomes were prospectively measured by blinded ICU doctors. A logistic regression model was developed to assess if HbA ₁ c predicts poor outcomes in these settings. Results: Nearly 24% of the participants had HbA ₁ c ≥ 6. Those with HbA ₁ c ≥ 6 had 3.14 times greater risk of poor outcome at the end of hospital stay when compared to those with HbA ₁ c < 6 and this risk increased to an odds ratio of 4.57 on adjusting for other significant predictors: Acute Physiology and Chronic Health Evaluation II, injury severity score, admission blood sugar and age at admission. Conclusions: Substantial proportion of trauma admissions has underlying diabetes. HbA ₁ c, a measure of pre admission glycaemic status is an important predictor of ICU outcome in trauma patients.