we used data from the third national health and nutrition examination survey ( nhanes iii ) mortality follow - up file ( 7 ) . for this database , the national center for health statistics linked nhanes iii participants aged 17 years by probabilistic matching to the national death index to determine mortality status through the year 2000 . for a selected sample of nhanes iii records ,
overall , 20,042 adult nhanes iii participants were eligible for matching , of whom 3,384 were identified as deceased ( 7 ) .
the mean observation time between the nhanes iii survey and ascertainment of mortality status was 7.58 years ( 95% ci 7.177.99 ) .
the underlying cause of death was based on icd-9 codes from 1986 to 1998 and on icd-10 codes from 1999 to 2000 .
death was classified from heart disease for icd-9 codes 390398 , 402 , and 404429 and icd-10 codes i00i09 , i11 , i13 , and i20i51 .
nhanes iii was conducted between 1988 and 1994 and used a stratified multistage sampling design with oversampling of mexican americans , african americans , and individuals over age 60 years . the survey consisted of multiple components including a household interview , a physical examination , and laboratory tests .
information on medical history was obtained during the household interview , and a total of 1,507 adults reported a diagnosis of diabetes . women who reported only gestational diabetes
this study was approved by the institutional review board at the va puget sound medical center .
physical activity was based on a self - report during the month before the survey .
individuals were classified as inactive if they did not report engaging in any of the following activities during the previous month : walking , jogging , bike riding , swimming , aerobics , dancing , calisthenics , gardening , lifting weights , or other physical activity outside of their occupation .
individuals were considered to fulfill national recommendations for physical activity if they reported five or more episodes per week of moderate - intensity physical activity , or three or more episodes per week of vigorous - intensity physical activity .
individuals reporting some physical activity during the preceding month but not at the recommended levels were classified as obtaining insufficient physical activity ( 8) .
current smokers were defined as people who had smoked > 100 cigarettes during their lifetime and were still smoking .
physical examination included measuring height , weight , blood pressure , and a blood draw .
a1c levels were classified as < 6% , between 6 and 7% , between 7 and 8% , and 8% to correspond to recent american diabetes association treatment guidelines ( 1 ) .
individuals were considered to have hypertension if they had a measured blood pressure of 140/90 mmhg or reported being told by their physician that they had high blood pressure and were on an antihypertensive medication .
bmi was calculated as the weight in kilograms divided by the squared height in meters ( 9 ) .
the national heart , lung and blood institute 's definition for the cutoff points between normal weight ( bmi 18.524.9 kg / m ) , overweight ( bmi 2529.9 kg / m ) , and obese ( bmi 30 kg / m ) were used ( 9 ) .
demographic information including age ( in years ) , sex , race / ethnicity ( white , african american , hispanic , or other ) , education ( less than high school , high school , or more than high school ) , and annual income were obtained at baseline during the interview portion of nhanes iii .
each observation was weighted to account for the unequal probability of selection that resulted from the survey cluster design , nonresponse , and oversampling of certain populations .
sampling weights were used to calculate population estimates , and sampling strata and clustering within primary sampling units were accounted for to estimate variances and test for significant differences .
all analyses thus took into account the complex survey design and weighted sampling probabilities and were performed using stata statistical software ( release 11 ; stata corporation , college station , tx ) .
we calculated hazard ratios ( hrs ) using cox proportional hazards regression with attained age at the time of censoring as the time scale ( 10,11 ) .
we divided data into three age strata ( age 1750 , 5165 , and > 65 years ) .
analyses were stratified by age - group , such that stratified estimates ( equal coefficients across strata but with a baseline hazard unique to each stratum ) were then obtained .
participants were censored at the end of the follow - up period if they were still alive .
cox proportional hazard models were used to estimate the combined effect of risk factors associated with mortality , controlling for sociodemographic factors ( annual income , race / ethnicity , sex , and education ) .
we calculated the par% for mortality among individuals with diabetes of known risk factors , including glycemic control , hypertension , hyperlipidemia , smoking , and physical inactivity .
par% was calculated as prevalence among decedents  [ ( hr  1)/hr ]  100% , where prevalence refers to the prevalence of the risk factor among individuals who died , and the hazard ratio ( hr ) is a multivariable - adjusted hazard ratio for mortality ( 12 ) .
par% can be interpreted as the percentage by which mortality rates could be lowered in all individuals with diabetes if the given exposure was abolished , assuming that the observed association is causal .
physical activity was based on a self - report during the month before the survey .
individuals were classified as inactive if they did not report engaging in any of the following activities during the previous month : walking , jogging , bike riding , swimming , aerobics , dancing , calisthenics , gardening , lifting weights , or other physical activity outside of their occupation .
individuals were considered to fulfill national recommendations for physical activity if they reported five or more episodes per week of moderate - intensity physical activity , or three or more episodes per week of vigorous - intensity physical activity .
individuals reporting some physical activity during the preceding month but not at the recommended levels were classified as obtaining insufficient physical activity ( 8) .
current smokers were defined as people who had smoked > 100 cigarettes during their lifetime and were still smoking .
physical examination included measuring height , weight , blood pressure , and a blood draw .
a1c levels were classified as < 6% , between 6 and 7% , between 7 and 8% , and 8% to correspond to recent american diabetes association treatment guidelines ( 1 ) .
individuals were considered to have hypertension if they had a measured blood pressure of 140/90 mmhg or reported being told by their physician that they had high blood pressure and were on an antihypertensive medication .
bmi was calculated as the weight in kilograms divided by the squared height in meters ( 9 ) .
the national heart , lung and blood institute 's definition for the cutoff points between normal weight ( bmi 18.524.9 kg / m ) , overweight ( bmi 2529.9 kg / m ) , and obese ( bmi 30 kg / m ) were used ( 9 ) .
demographic information including age ( in years ) , sex , race / ethnicity ( white , african american , hispanic , or other ) , education ( less than high school , high school , or more than high school ) , and annual income were obtained at baseline during the interview portion of nhanes iii .
each observation was weighted to account for the unequal probability of selection that resulted from the survey cluster design , nonresponse , and oversampling of certain populations .
sampling weights were used to calculate population estimates , and sampling strata and clustering within primary sampling units were accounted for to estimate variances and test for significant differences .
all analyses thus took into account the complex survey design and weighted sampling probabilities and were performed using stata statistical software ( release 11 ; stata corporation , college station , tx ) .
we calculated hazard ratios ( hrs ) using cox proportional hazards regression with attained age at the time of censoring as the time scale ( 10,11 ) .
we divided data into three age strata ( age 1750 , 5165 , and > 65 years ) .
analyses were stratified by age - group , such that stratified estimates ( equal coefficients across strata but with a baseline hazard unique to each stratum ) were then obtained .
participants were censored at the end of the follow - up period if they were still alive .
cox proportional hazard models were used to estimate the combined effect of risk factors associated with mortality , controlling for sociodemographic factors ( annual income , race / ethnicity , sex , and education ) .
we calculated the par% for mortality among individuals with diabetes of known risk factors , including glycemic control , hypertension , hyperlipidemia , smoking , and physical inactivity .
par% was calculated as prevalence among decedents  [ ( hr  1)/hr ]  100% , where prevalence refers to the prevalence of the risk factor among individuals who died , and the hazard ratio ( hr ) is a multivariable - adjusted hazard ratio for mortality ( 12 ) .
par% can be interpreted as the percentage by which mortality rates could be lowered in all individuals with diabetes if the given exposure was abolished , assuming that the observed association is causal .
overall , 1,507 adults with diabetes were eligible for mortality follow - up . for nhanes iii participants with diabetes , 865 were assumed to be alive by virtue of not being identified in the national death index , and 642 were deceased during the follow - up period .
overall , 53% of deaths were from cardiovascular disease , 17% were from cancer , and 29% were from other causes of death .
the population characteristics of the sample and cumulative mortality by exposure group are displayed on table 1 .
older individuals and individuals with less education were more likely to have died in the follow - up period .
table 2 displays the results of the cox proportional hazard model for death and the par% for each risk factor . among adults with diabetes ,
the hrs for all - cause mortality were significant for individuals who had an a1c 8% ( hr 1.65 , 95% ci 1.112.45 ) or reported no regular physical activity ( 1.58 , 1.242.02 ) or current tobacco use ( 1.77 , 1.152.73 ) .
8% , 16.4% for no regular physical activity , and 7.5% for current tobacco use . population characteristics and cumulative mortality of individuals with diabetes in nhanes iii proportional hazards analysis results from all - cause mortality : nhanes iii mortality follow - up par% = prevalence among decedents  [ ( hr  1)/hr ] .
in this nationally representative sample of individuals with diabetes , we found three statistically significant risk factors for all - cause mortality .
we estimate that mortality rates could be decreased by 15.3 , 16.4 , and 7.5% , respectively , if the following risk factors were eliminated : having an a1c of 8% , physical inactivity , or current smoking .
there is evidence from several observational studies that higher levels of physical activity confer protection against premature coronary disease and early mortality . in a study using the nhanes mortality data , rask et al . ( 5 ) also showed a similar effect of smoking and physical inactivity on mortality .
this study did not focus specifically on individuals with diabetes or present par% ( 5 ) . in a study of women with diabetes ,
the age - adjusted relative risk for cardiovascular disease was 0.54 ( 95% ci 0.390.76 ) for women who performed 4 h of moderate or vigorous exercise per week ( 14 ) .
wei et al . ( 15 ) reported that the relative risk of mortality was 1.7 ( 95% ci 1.22.3 ) in 1,263 men with diabetes with low levels of physical activity followed on average for 12 years . in a national study , u.s .
adults with diabetes who walked at least 2 h / week had a 39% lower all - cause mortality ( 16 ) .
previous studies have shown that cigarette smoking is strongly associated with an increased risk of coronary heart disease among individuals with diabetes , even more so than individuals without diabetes , and quitting smoking decreases this excess risk substantially ( 17 ) .
our results are consistent with other studies that have identified a protective effect of moderate glucose control ( 3,18 ) .
( 3 ) used nhanes iii data to examine a1c level and subsequent mortality among adults in the u.s .
these authors reported that among individuals with diabetes , having an a1c of 8% was associated with higher all - cause mortality risk ( hr 1.68 , 95% ci 1.032.74 ) , compared with adults with an a1c of < 6% , which is similar to our findings .
however , this study did not examine the effect of physical activity or present population - attributable risks ( 3 ) . despite clinical trial data to support blood pressure and lipid control among individuals with diabetes ( 19,20 ) ,
these factors were not significant in our study , although the hazard ratios were in the expected direction .
these nonstatistically significant findings may be a result of insufficient power in the current study .
in addition , since nhanes iii data were collected , the complexity of care for individuals with diabetes has increased , including the use of antihypertensive and antilipemic agents ( 21 ) .
our results are consistent with older hnanes data from 1982 to 1984 on risk factors for mortality from all causes and from coronary heart disease among individuals with diabetes ( 4 ) .
this study reported that age , male sex , severe overweight ( defined as a bmi 31.1 kg / m for men and 32.3 kg / m for women ) , and nonleisure time physical inactivity were associated with coronary heart disease mortality among persons with diabetes .
neither cholesterol nor hypertension were found to be associated with coronary heart disease mortality in this population of individuals with diabetes ( 4 ) .
limitations of our study include the potential biases introduced by the self - report of health conditions and level of physical activity .
because we do not know the actual duration of physical activity and do not have information on nonleisure physical activity , total activity levels may be underestimated .
in addition , estimates of par% from observational data make an implicit assumption of causality : that abolishing exposure would , in fact , reduce risk to the level observed among unexposed individuals .
we could also over- or underestimate par% because of the assumption that the prevalence of other risk factors would remain the same if one of them were changed ( 22 ) . in practice
, a particular intervention aimed at one risk factor could alter population levels of other risk factors , either favorably or unfavorably .
par% also assumes that the other risk factors not included in our regression model are uncorrelated with the target exposure ; in fact , risk factors may cluster within people .
unlike measures of association such as relative risk , par% depends on both the strength of the association between the exposure and disease and the prevalence of the exposure in the population ( 6 ) .
in contrast , the relative risk offers a measure of the strength of association between the risk ( e.g. , degree of hyperglycemia ) and mortality for the average individual .
par% can assess the potential benefit to be gained for a population rather than for individual - level interventions . in conclusion , we found significant associations between physical inactivity , smoking and poor glycemic control , and all - cause mortality among individuals with diabetes .
previous reports have demonstrated poor adherence to physical activity recommendations by individuals with diabetes ( 23 ) and low rates of physical activity and smoking cessation counseling by physicians ( 21 ) .
clinicians and health systems may consider prioritizing their care to include avoidance of tobacco and increasing physical activity levels among all patients with diabetes ( 24 ) .
population - based programs ( e.g. , quality improvement efforts ) for individuals with diabetes may consider prioritizing these areas , especially given limited improvements in mortality rates among individuals with diabetes over the past 2 decades ( 25 ) .
 objectivelittle is known about the relative contributions of modifiable risk factors to overall diabetes mortality . 
 the purpose of the current study is to 1 ) assess the association between modifiable risk factors and all - cause mortality among a nationally representative sample of individuals with diabetes and 2 ) determine the population - attributable risk percent ( par% ) for these factors.research design and methodswe analyzed data from a nationally representative sample of 1,507 adults over the age of 17 years with a self - reported diagnosis of diabetes from the third national health and nutrition examination survey ( nhanes iii ) mortality study . 
 our main outcome measures were all - cause mortality and par% . 
 we used the cox proportional hazard analysis to determine hazard ratios ( hrs ) for known diabetes risks and calculated par%.resultsamong adults with diabetes , the hrs for all - cause mortality were significant for individuals who had an a1c 8% ( hr 1.65 , 95% ci 1.112.45 ) or reported no regular physical activity ( 1.58 , 1.242.02 ) or current tobacco use ( 1.77 , 1.152.73 ) . 
 the population - attributable risk was 15.3% for a1c value 8% , 16.4% for no regular physical activity , and 7.5% for current tobacco use.conclusionshealth systems may consider prioritizing care to include smoking cessation , increasing physical activity , and moderate glycemic control among patients with diabetes . 
 this study suggests that focusing on these areas may result in significant reductions in mortality in individuals with diabetes . 