analyses included data released from 96,405 patients hospitalized for different pathologies at san giovanni battista hospital of turin , a large teaching general hospital excluding departments of ophthalmology , obstetrics and gynecology , and pediatrics and infectious diseases , between 1 october 2003 and 30 september 2006 . for every patient , administrative records were linked with the laboratory measurements dataset of plasma glucose . of the 96,405 admissions , 26,409 ( 27.4% ) were excluded because plasma glucose was not measured upon admission to the hospital . from this cohort , related groups ( apr - drgs ) and their relative risk of death ( riskd ) ( 6 ) . based severity measurement systems taking into consideration the principal diagnosis , age , interactions of multiple secondary diagnoses , and combinations of nonoperating procedures incorporated with the principal diagnosis of subjects . among the 3,401 deaths , 63 records ( 62 with an apr - drg 196 , cardiac arrest , unexplained ,  and 1 with apr - drg 130 ,  respiratory system diagnosis with ventilator support 96 + hours  ) were excluded from the study because we could not find a surviving control subject . a total of 3,338 cases were thus matched with a random sample of control subjects within each matching stratum . this procedure led to a set of 6,676 patients perfectly balanced for apr and riskd distribution . all plasma glucose measurements were determined in a central laboratory with a glucose analyzer ( roche / hitachi modular d analyser : acn 767 , indianapolis , in ) . we performed a multivariate conditional logistic regression model to evaluate the associations between in - hospital mortality and a set of variables including demographic characteristics ( sex , age , marital status , and level of education ) and clinical characteristics ( type of admission , type of treatment , and plasma glucose on admission ) . apr - drgs and riskd , as matching variables , were not included in the model . plasma glucose measurements were added to the model as restricted cubic spline to investigate the association between in - hospital death and plasma glucose levels through a straight and smooth line outside the whole interval of values . values of plasma glucose minimizing the risk of death were determined using the inverse spline function , and 95% cis were derived from bootstraps with 1,000 runs . the whole population with plasma glucose available at admission presents 69,996 cases ( mean 65 years of age [ range 5175 ] ; 42% female ; 5% dead ) . within this group , we analyzed a cohort of 3,338 cases ( dead ) versus 3,338 control subjects ( alive ) ( mean 70 years of age [ 5978 ] vs. 73 years of age [ 6380 ] ; 40 vs. 42% female ; and mean 99 mg / dl [ 82128 ] vs. 107 mg / dl [ 85144 ] plasma glucose on admission ) . the effect of plasma glucose adjusted by administration data was nonlinear , as described in fig . , the minimal risk of in - hospital mortality was found at plasma glucose levels of mean 89 mg / dl ( range 78101 ) . the adjusted odds ratio ( or ) of deaths for plasma glucose on admission from 100 to 200 mg / dl is 1.32 ( 95% ci 1.221.43 ) , whereas the or for plasma glucose from 60 to 80 mg / dl is 1.06 ( 1.041.07 ) . a significant number of in - hospital patients display hyperglycemia , which can be the cause of admission or , more frequently , comorbidity . previous reports ( 79 ) have pointed out the relationship between hyperglycemia and prognosis in critically ill patients . the main novelty of the present study is that even moderate glucose elevations or reductions are associated with increased in - hospital mortality in this heterogeneous population . in this study , we have analyzed a large cohort of patients hospitalized for multiple pathologies with a nested case - control study . furthermore , our observations strongly suggest that , independently of the cause of hospitalization , a patient with an optimal plasma glucose measure between 78 and 101 mg / dl displays lower risk of death . interestingly , this optimal glycemic range is closely related to normoglycemic values as defined by criteria of the american diabetes association ( 10 ) . the retrospective design prevents concluding whether hypo- or hyperglycemia was a cause of increased mortality or just a marker of increased risks of mortality , although we do observe a strong association between hospital mortality and glycemic levels . other limitations are 1 ) missing data for 27.4% of all admitted patients ( this data gap could be the consequence of the use of point - of - care procedures)in any case , within this group , the mortality rate was only 3.5% ; 2 ) some specialties were excluded from the study because they were allocated to other hospitals ; 3 ) we do not know the duration of hypo- or hyperglycemia ; and 4 ) hypoglycemic values could result from diabetes therapy or critical diseases . however , these data confirm the importance of glycemic value upon hospital admission ( 11 ) . lowest hospital mortality rates were observed among patients with plasma glucose concentrations between 78 and 101 mg / dl , and even a moderate variation below or above these cutoff values may increase mortality in a heterogeneous group of patients .
objective  hyperglycemia is a common condition in hospitalized patients . 
 the aim of this study was to investigate the relationships between glycemia upon admission and mortality in a heterogeneous group of adult patients.research design and methods 
 the 3-year records released from a general hospital were associated with a plasma glucose dataset of its general laboratory . 
 a matched case - control study was implemented ( 3,338 case - control subject pairs ) . 
 all - patient refined diagnosis 
 related groups and the relative risk of death were the matching criteria . 
 a multivariate conditional logistic regression model was used to evaluate the associations between death and glycemia.resultshigher in - hospital mortality was associated with hyperglycemia or hypoglycemia , whereas lower risk was observed for values between 78 and 101 mg / dl.conclusions  our data confirm the relation between glycemia upon admission and mortality and suggest that slightly increased or decreased plasma glucose can be linked with increased mortality risk .