AIM:To compare mortality risks associated with known diabetic patients to hyperglycemic non-diabetic patients.METHODS:PubMed data base was searched for patients with sepsis,bacteremia,mortality and diabetes.Articles that also identified new onset hyperglycemia (NOH) (fasting blood glucose>125 mg/dL or random blood glucose>199 mg/dL) were identified and reviewed.Nine studies were evaluated with regards to hyperglycemia and hospital mortality and five of the nine were summarized with regards to intensive care unit (ICU) mortality.RESULTS:Historically hyperglycemia has been believed to be equally harmful in known diabetic patients and non-diabetics patients admitted to the hospital.Unexpectedly,having a history of diabetes when admitted to the hospital was associated with a reduced risk of hospital mortality.Approximately 17% of patients admitted to hospital have NOH and 24% have diabetes mellitus.Hospital mortality was significantly increased in all nine studies of patients with NOH as compared to known diabetic patients (26.7%±3.4% vs 12.5% ±3.4%,P<0.05;analysis of variance).Unadjusted ICU mortality was evaluated in five studies and was more than doubled for those patients with NOH as compared to known diabetic patients (25.3%±3.3% vs 12.8%±2.6%,P<0.05) despite having similar blood glucose concentrations.Most importantly,having NOH was associated with an increased ICU and a 2.7-fold increase in hospital mortality when compared to hyperglycemic diabetic patients.The mortality benefit of being diabetic is unclear but may have to do with adaptation to hyperglycemia over time.Having a history of diabetes mellitus and prior episodes of hyperglycemia may provide time for the immune system to adapt to hyperglycemia and result in a reduced mortality risk.Understanding why diabetic patients have a lower than expected hospital mortality rate even with bacteremia or acute respiratory distress syndrome needs further study.CONCLUSION:Having hyperglycemia without a history of previous diabetes mellitus is a major independent risk factor for ICU and hospital mortality. AIM: To compare mortality risks associated with known diabetic patients to hyperglycemic non-diabetic patients. METHODS: PubMed data base was searched for patients with sepsis, bacteremia, mortality and diabetes. Articles that also identified new onset hyperglycemia (NOH) (fasting blood glucose > 125 mg / dL or random blood glucose> 199 mg / dL) were identified and reviewed. Nine studies were evaluated with regards to hyperglycemia and hospital mortality and five of the nine were summarized with regards to intensive care unit (ICU) mortality .RESULTS : Historically hyperglycemia has been believed to be equally harmful in known diabetic patients and non-diabetics patients admitted to the hospital. Unexpectedly, having a history of diabetes when admitted to the hospital was associated with reduced risk of hospital mortality. Appximately 17% of patients admitted to hospital have NOH and 24% have diabetes mellitus. Hospitality was significantly increased in all nine studies of patients with NOH as c oduared to known diabetic patients (26.7% ± 3.4% vs 12.5% ​​± 3.4%, P <0.05; analysis of variance) .Unadjusted ICU mortality was evaluated in five studies and was more than double for those patients with NOH as compared to known diabetic patients who had NOH was associated with an increased ICU and a 2.7-fold increase in hospital mortality when compared to hyperglycemic diabetic (25.3% ± 3.3% vs 12.8% ± 2.6%, P <0.05) patients. the mortality benefit of being being diabetic is unclear but may have to with with adaptation to hyperglycemia over time. Having a history of diabetes mellitus and prior episodes of hyperglycemia may provide for the immune system to adapt to hyperglycemia and result in a reduced mortality risk.Understanding why diabetic patients have a lower than expected hospital mortality rate even with bacteremia or acute respiratory distress syndrome needs further study. CONCLUSION: Having hyperglycemia without a history of previous diabetes mellitus is a major independent risk factor for ICU and hospital mortality.