study participants were members of the cardiovascular health study ( chs ) , a prospective cohort consisting of 5,888 men and women aged 65 years who were randomly selected from medicare - eligibility lists in four u.s .
communities ( forsyth county , nc ; washington county , md ; sacramento county , ca ; and pittsburgh , pa ) . a detailed description of methods and procedures in the chs has previously been published ( 26 ) .
briefly , persons eligible to participate were not institutionalized or wheelchair dependent , did not require a proxy for consent , were not receiving treatment for cancer , and were expected to remain in their respective regions for 3 years . from 1989 to 1990 , 5,201 participants were recruited in the original cohort . between 1992 and 1993 , 687 subjects ( predominantly african american ) were also recruited .
baseline evaluation of study participants included standardized questionnaires , physical examination , anthropometric measurements , resting electrocardiography , and laboratory examinations . from 1989 through 1999 , participants were followed up every 6 months , alternating between telephone calls and clinic visits ; biennial telephone calls have continued since then .
the institutional review board at each center approved the study , and each participant gave informed consent .
for this analysis , the 19921993 clinic visit was used as baseline . of the 5,553 participants alive at the 19921993 clinic visit
, we excluded 773 people with prevalent diabetes , 780 people with missing data on fabp4 and nefa , 205 people with missing data on prevalent or incident type 2 diabetes , and 55 individuals with missing covariate information .
plasma samples collected at the 19921993 examination were stored at 70c until analyzed at the central laboratory at the university of vermont .
the interassay coefficient of variation ( cv ) was 2.615.32% ( detectable range 5250 ng / ml ) .
this technique relies on the acylation of coa by the fatty acids in the presence of added acyl - coa synthetase .
acyl - coa produced is oxidized by added acyl - coa oxidase with generation of hydrogen peroxide and in the presence of peroxidase permits the oxidative condensation of 3-methy - n - ethyl - n(-hydroxyethyl)-aniline with 4-aminoantipyrine to form a purple - colored adduct .
we assessed medication use at baseline and annually by a validated medication inventory ( 27 ) through 2007 .
in addition , fasting glucose was measured on blood specimens from the examinations in years 19921993 , 19961997 , 19981999 , and 20052006 ; nonfasting glucose was measured on blood specimens from 1994 to 1995 .
a participant was classified as having type 2 diabetes if any of the following conditions were met : 1 ) use of insulin or oral hypoglycemic agents , 2 ) fasting glucose level of 7 mmol / l ( 126 mg / dl ) , or 3 ) a nonfasting glucose level of 11.1 mmol / l ( 200 mg / dl ) .
age , sex , race , years of education , smoking status , and alcohol consumption were based on self - report .
leisure - time activity ( kilocalories per week ) was assessed using a modified minnesota leisure - time activities questionnaire ( 28 ) .
bmi was calculated as weight in kilograms divided by the square of height in meters .
missing values for smoking and height to calculate bmi were carried forward from previous years if available .
serum albumin was assessed using the kodak ektachem 700 analyzer ( eastman kodak , rochester , ny ) .
plasma triglyceride was measured by enzymatic methods on an olympus demand system ( olympus , lake success , ny ) .
hdl was measured by an enzymatic method after precipitation of apolipoprotein b  containing lipoproteins with dextran sulfate / magnesium sulfate .
interassay cvs using reference standards for triglycerides and hdl were 1.78 and 2.15% , respectively .
cystatin c was measured by nephelometer using a particle - enhanced immunonephelometric assay ( n latex cystatin c ; dade behring , newark , de ) ( 30 ) with a interassay cv of 2.93.3% .
baseline characteristics of study participants were summarized according to categories of fabp4 and nefa ; continuous variables were presented as means  sd and categorical variables as percentages .
cox proportional hazards regression was used to estimate the association of fabp4 and nefa with incident type 2 diabetes to allow adjustment for covariates .
because the distribution of fabp4 differed appreciably between men and women , fabp4 was modeled as sex - specific tertiles with the lowest tertile as the referent category .
nefa was similarly modeled as tertiles based on the overall distribution and also continuously per sd .
individuals were censored for death , loss to follow - up , or end of diabetes ascertainment ( 20062007 ) .
potential confounders included in adjusted models were age , race , and sex ( where appropriate ) ( model 1 ) with the addition of bmi ( included in nefa model only ) , education ( less than high school versus high school or more ) , cystatin c ( log transformed and included in fabp4 model only ) , serum albumin ( included in nefa model only ) , kilocalories of physical activity ( log transformed ) , alcohol intake ( none and < 0.5 , 0.51 , and > 1 drinks / day for women ; none and < 1 , 12 , and > 2 drinks / day for men ) , smoking status ( never , former , and current ) , self - reported health status ( fair / poor versus better ) , and estrogen use for women ( model 2 ) .
given the production of fabp4 in adipocytes , we examined interaction between bmi and fabp4 . to evaluate intermediate pathways by which fabp4 might lead to type 2 diabetes , we adjusted for c - reactive protein ( log transformed ) , homa - ir , triglycerides ( log transformed ) , hdl , and ldl . to evaluate the joint impact of fabp4 and nefa on diabetes risk
we also tested for an interaction between fabp4 and nefa on the risk of incident type 2 diabetes .
in secondary analyses , we evaluated whether there were statistically significant interactions between log fabp4 and age or waist circumference or between nefa and sex or bmi . because measured weight may not always reflect adiposity in older adults , we excluded participants with unintentional weight loss ( defined as self - reported loss of 10 pounds not due to diet or exercise during the past 12 months ) , prevalent cardiovascular disease ( coronary heart disease or stroke ) , or cancer in a sensitivity analysis .
since plasma nefa varies with dietary intake ( 31 ) and lipid metabolism and a single measure may not be a good estimate of average concentrations over the long term , we repeated the analysis while restricting follow - up to the first 5 years .
schoenfeld residuals and plots of the residuals over time were used to evaluate proportional hazards assumptions ; there were no meaningful violations .
stata , version 11.1 ( statacorp , college station , texas ) , was used for all analyses , and p values < 0.05 were considered statistically significant .
plasma samples collected at the 19921993 examination were stored at 70c until analyzed at the central laboratory at the university of vermont .
the interassay coefficient of variation ( cv ) was 2.615.32% ( detectable range 5250 ng / ml ) .
this technique relies on the acylation of coa by the fatty acids in the presence of added acyl - coa synthetase .
acyl - coa produced is oxidized by added acyl - coa oxidase with generation of hydrogen peroxide and in the presence of peroxidase permits the oxidative condensation of 3-methy - n - ethyl - n(-hydroxyethyl)-aniline with 4-aminoantipyrine to form a purple - colored adduct .
we assessed medication use at baseline and annually by a validated medication inventory ( 27 ) through 2007 .
in addition , fasting glucose was measured on blood specimens from the examinations in years 19921993 , 19961997 , 19981999 , and 20052006 ; nonfasting glucose was measured on blood specimens from 1994 to 1995 .
a participant was classified as having type 2 diabetes if any of the following conditions were met : 1 ) use of insulin or oral hypoglycemic agents , 2 ) fasting glucose level of 7 mmol / l ( 126 mg / dl ) , or 3 ) a nonfasting glucose level of 11.1 mmol / l ( 200 mg / dl ) .
age , sex , race , years of education , smoking status , and alcohol consumption were based on self - report .
leisure - time activity ( kilocalories per week ) was assessed using a modified minnesota leisure - time activities questionnaire ( 28 ) .
bmi was calculated as weight in kilograms divided by the square of height in meters .
missing values for smoking and height to calculate bmi were carried forward from previous years if available .
serum albumin was assessed using the kodak ektachem 700 analyzer ( eastman kodak , rochester , ny ) .
plasma triglyceride was measured by enzymatic methods on an olympus demand system ( olympus , lake success , ny ) .
hdl was measured by an enzymatic method after precipitation of apolipoprotein b  containing lipoproteins with dextran sulfate / magnesium sulfate .
interassay cvs using reference standards for triglycerides and hdl were 1.78 and 2.15% , respectively .
cystatin c was measured by nephelometer using a particle - enhanced immunonephelometric assay ( n latex cystatin c ; dade behring , newark , de ) ( 30 ) with a interassay cv of 2.93.3% .
baseline characteristics of study participants were summarized according to categories of fabp4 and nefa ; continuous variables were presented as means  sd and categorical variables as percentages .
cox proportional hazards regression was used to estimate the association of fabp4 and nefa with incident type 2 diabetes to allow adjustment for covariates .
because the distribution of fabp4 differed appreciably between men and women , fabp4 was modeled as sex - specific tertiles with the lowest tertile as the referent category .
nefa was similarly modeled as tertiles based on the overall distribution and also continuously per sd .
individuals were censored for death , loss to follow - up , or end of diabetes ascertainment ( 20062007 ) .
potential confounders included in adjusted models were age , race , and sex ( where appropriate ) ( model 1 ) with the addition of bmi ( included in nefa model only ) , education ( less than high school versus high school or more ) , cystatin c ( log transformed and included in fabp4 model only ) , serum albumin ( included in nefa model only ) , kilocalories of physical activity ( log transformed ) , alcohol intake ( none and < 0.5 , 0.51 , and > 1 drinks / day for women ; none and < 1 , 12 , and > 2 drinks / day for men ) , smoking status ( never , former , and current ) , self - reported health status ( fair / poor versus better ) , and estrogen use for women ( model 2 ) .
given the production of fabp4 in adipocytes , we examined interaction between bmi and fabp4 . to evaluate intermediate pathways by which fabp4 might lead to type 2 diabetes
, we adjusted for c - reactive protein ( log transformed ) , homa - ir , triglycerides ( log transformed ) , hdl , and ldl . to evaluate the joint impact of fabp4 and nefa on diabetes risk
we also tested for an interaction between fabp4 and nefa on the risk of incident type 2 diabetes .
in secondary analyses , we evaluated whether there were statistically significant interactions between log fabp4 and age or waist circumference or between nefa and sex or bmi . because measured weight may not always reflect adiposity in older adults , we excluded participants with unintentional weight loss ( defined as self - reported loss of 10 pounds not due to diet or exercise during the past 12 months ) , prevalent cardiovascular disease ( coronary heart disease or stroke ) , or cancer in a sensitivity analysis .
since plasma nefa varies with dietary intake ( 31 ) and lipid metabolism and a single measure may not be a good estimate of average concentrations over the long term , we repeated the analysis while restricting follow - up to the first 5 years .
schoenfeld residuals and plots of the residuals over time were used to evaluate proportional hazards assumptions ; there were no meaningful violations .
stata , version 11.1 ( statacorp , college station , texas ) , was used for all analyses , and p values < 0.05 were considered statistically significant .
among 3,740 participants , 2,259 were women ( 60% ) and the mean age at baseline was 74.8 years ( range 6598 ) .
median plasma fabp4 was 29.5 ng / ml ( interquartile range 22.039.3 ) , and women had substantially higher concentrations of fabp4 ( median 34.4 ng / ml ) than men ( median 22.8 ng / ml ) .
compared with the lowest tertile of fabp4 , those in the highest tertile had higher measures of adiposity and were more likely to have insulin resistance , higher prevalence of dyslipidemia , poorer health , higher levels of cystatin c , and lower physical activity .
details on correlation coefficients between fabp4 and risk factors for type 2 diabetes are presented in supplementary table 1 .
characteristics of 3,740 participants by sex - specific tertiles of fabp4 in the chs during a mean follow - up of 9.5 years , 305 cases of incident diabetes occurred .
hazard ratios ( hrs ) associated with each sd increase in log fabp4 were 1.39 ( 95% ci 1.191.62 ) overall , 1.35 ( 1.101.65 ) for women , and 1.45 ( 1.131.85 ) for men after adjustment for age , race , sex , education , physical activity , cystatin c , alcohol intake , smoking , self - reported health status , and estrogen use for women ( table 2 ) , p for sex - by - fabp4 interaction 0.10 ) .
there was evidence for an interaction between bmi and fabp4 on the risk of diabetes ( p value for interaction between continuous bmi and log fabp4 : p = 0.009 overall , 0.02 for women , and 0.135 for men ) ( table 3 ) .
fabp4 was associated with diabetes in people with lower bmi in both sexes , but the only significantly elevated risk was among lean men ( table 3 ) . incidence rate and hrs of type 2 diabetes according to fabp4 tertiles or sd of log fabp4 ( 0.46 ) in the chs hr of diabetes per sd increase in log fabp4 stratified by bmi in the chs * as expected , additional adjustment for potential mediating factors ( c - reactive protein , homa - ir , ldl and hdl cholesterol , and triglycerides ) attenuated the observed association further ( relative risk [ rr ] per sd increase of log fabp4 of 1.25 [ 95% ci 1.011.55 ] ) for women and 1.17 [ 0.901.53 ] for men ) .
relations between each potential mediator and type 2 diabetes when added individually to the full model are shown in supplementary table 2 .
there was no statistically significant interaction between fabp4 and nefa ( p = 0.16 ) , and results were similar with the addition of nefa to these models ( data not shown ) . in a sensitivity analysis ,
exclusion of individuals with reported unintentional weight loss , prevalent cardiovascular disease , and cancer tended to strengthen the association ( hr per sd increase in log fabp4 from 1.39 [ 95% ci 1.191.62 ] before exclusion to 2.42 [ 1.563.73 ] after exclusion for men and women combined ) .
participants with higher concentrations of nefa were older , were more likely to be female , had higher measures of adiposity , and had higher levels of total cholesterol , triglycerides , hdl , and c - reactive protein levels ( supplementary table 3 ) . in a multivariable model adjusted for age , sex , ethnicity , education , bmi , leisure - time physical activity ( kilocalories ) ,
smoking , alcohol use , health status , estrogen use ( in women ) , and serum albumin , the hr associated with each sd of nefa ( 0.20
meq / l ) was 1.08 ( 95% ci 0.961.23 ) ( table 4 ) .
results were similar with the addition of fabp4 to these models ( data not shown ) .
when stratified by bmi ( < 25 , 2529.9 , and 30 kg / m ) , the results did not change materially and the p value for bmi - by - nefa interaction was 0.13 . in a secondary analysis restricted to the first 5 years of follow up , each sd of higher nefa was associated with an hr of 1.15 ( 0.971.36 ) in a fully adjusted model , and there was evidence for increased risk of diabetes at higher levels of nefa when analyzed by tertiles of nefa ( 1.0 [ ref . ] , 1.68 [ 95% ci 1.122.53 ] , and 1.63 [ 1.072.50 ] ) ( table 4 ) .
there was no evidence for sex - by - nefa interaction ( p = 0.97 ) .
hr ( 95% ci ) of diabetes by category of and per sd ( 0.20 meq / l ) increase in nefas in the chs
table 1 presents baseline characteristics of subjects according to tertiles of fabp4 by sex . compared with the lowest tertile of fabp4 , those in the highest tertile had higher measures of adiposity and were more likely to have insulin resistance , higher prevalence of dyslipidemia , poorer health , higher levels of cystatin c , and lower physical activity .
details on correlation coefficients between fabp4 and risk factors for type 2 diabetes are presented in supplementary table 1 .
characteristics of 3,740 participants by sex - specific tertiles of fabp4 in the chs during a mean follow - up of 9.5 years , 305 cases of incident diabetes occurred .
hazard ratios ( hrs ) associated with each sd increase in log fabp4 were 1.39 ( 95% ci 1.191.62 ) overall , 1.35 ( 1.101.65 ) for women , and 1.45 ( 1.131.85 ) for men after adjustment for age , race , sex , education , physical activity , cystatin c , alcohol intake , smoking , self - reported health status , and estrogen use for women ( table 2 ) , p for sex - by - fabp4 interaction 0.10 ) .
there was evidence for an interaction between bmi and fabp4 on the risk of diabetes ( p value for interaction between continuous bmi and log fabp4 : p = 0.009 overall , 0.02 for women , and 0.135 for men ) ( table 3 ) .
fabp4 was associated with diabetes in people with lower bmi in both sexes , but the only significantly elevated risk was among lean men ( table 3 ) . incidence rate and hrs of type 2 diabetes according to fabp4 tertiles or sd of log fabp4 ( 0.46 ) in the chs hr of diabetes per sd increase in log fabp4 stratified by bmi in the chs * as expected , additional adjustment for potential mediating factors ( c - reactive protein , homa - ir , ldl and hdl cholesterol , and triglycerides ) attenuated the observed association further ( relative risk [ rr ] per sd increase of log fabp4 of 1.25 [ 95% ci 1.011.55 ] ) for women and 1.17 [ 0.901.53 ] for men ) .
relations between each potential mediator and type 2 diabetes when added individually to the full model are shown in supplementary table 2 .
there was no statistically significant interaction between fabp4 and nefa ( p = 0.16 ) , and results were similar with the addition of nefa to these models ( data not shown ) . in a sensitivity analysis ,
exclusion of individuals with reported unintentional weight loss , prevalent cardiovascular disease , and cancer tended to strengthen the association ( hr per sd increase in log fabp4 from 1.39 [ 95% ci 1.191.62 ] before exclusion to 2.42 [ 1.563.73 ] after exclusion for men and women combined ) .
participants with higher concentrations of nefa were older , were more likely to be female , had higher measures of adiposity , and had higher levels of total cholesterol , triglycerides , hdl , and c - reactive protein levels ( supplementary table 3 ) . in a multivariable model adjusted for age , sex , ethnicity , education , bmi , leisure - time physical activity ( kilocalories ) , smoking , alcohol use , health status , estrogen use ( in women ) , and
serum albumin , the hr associated with each sd of nefa ( 0.20 meq / l ) was 1.08 ( 95% ci 0.961.23 ) ( table 4 ) .
results were similar with the addition of fabp4 to these models ( data not shown ) .
when stratified by bmi ( < 25 , 2529.9 , and 30 kg / m ) , the results did not change materially and the p value for bmi - by - nefa interaction was 0.13 . in a secondary analysis restricted to the first 5 years of follow up , each sd of higher nefa was associated with an hr of 1.15 ( 0.971.36 ) in a fully adjusted model , and there was evidence for increased risk of diabetes at higher levels of nefa when analyzed by tertiles of nefa ( 1.0 [ ref .
] , 1.68 [ 95% ci 1.122.53 ] , and 1.63 [ 1.072.50 ] ) ( table 4 ) . there was no evidence for sex - by - nefa interaction ( p = 0.97 ) .
hr ( 95% ci ) of diabetes by category of and per sd ( 0.20 meq / l ) increase in nefas in the chs
in this prospective study of 3,740 people , we demonstrate a positive association between plasma fabp4 and incident type 2 diabetes in older adults and such association was modified by bmi in a way that a statistically significant higher risk of diabetes with fabp4 was observed in lean men only .
we also observed a significant positive association between plasma nefa and incident type 2 diabetes during the first 5 years that was attenuated and not statistically significant when the total follow - up period was considered .
this association was not materially altered with adjustments for fabp4 , and there was no interaction between fabp4 and nefa with incident type 2 diabetes . to the best of our knowledge ,
this is the first large prospective study to evaluate associations between plasma fabp4 and incident type 2 diabetes among older men and women in a community setting . while several animal studies have examined the effects of fabp4 expression on adiposity , insulin resistance , and type 2 diabetes risk ( 7,10,11,32 ) , there are only limited data available in humans . in a cross - sectional study of 98 patients with coronary artery disease , serum levels of fabp4
were positively correlated with the prevalence of metabolic syndrome ( mets ) ( p = 0.037 ) and the number of mets components ( p = 0.035 ) ( 33 ) . in another cross - sectional study of 806 middle - aged men and women ,
each sd of higher log fabp4 was associated with a 1.85-fold increased odds of mets ( 95% ci 1.532.23 ) controlling for age , sex , and race ( 5 ) .
( 8) ( n = 229 ) and stejskal and karpisek ( 6 ) ( n = 138 ) have reported positive associations between serum concentrations of fabp4 and mets .
baseline fabp4 was also shown to be associated with incident mets after 5 years of follow - up in 356 chinese individuals ( 9 ) .
only one study has evaluated the association of fabp4 levels with incident type 2 diabetes . in a 10-year prospective study of 544 chinese participants with a mean age of 50 years , fabp4 levels above the population median ( 15.3 ng / ml for men and 20.4 ng / ml for women )
were associated with a twofold increased risk of type 2 diabetes after controlling for bmi and other confounding factors ( rr 2.25 [ 95% ci 1.403.65 ] ) ( 16 ) .
we found that the association of fabp4 with type 2 diabetes risk was most pronounced in persons with bmi < 25 kg / m . in light of this finding , it is notable that the above chinese study has a lower bmi ( mean  sd 24.3  3.7 kg / m ) than the chs study ( 26.4  4.6 kg / m ) ( 16 ) .
the interaction between bmi and fabp4 is consistent with the positive association seen in the leaner chinese cohort .
our working hypothesis is that expression of fabp4 may be directly associated with the size of adipocytes ; furthermore , we are hypothesizing that overweight / obese subjects have larger adipocyte size than lean people .
our findings of no overall significant association between nefa and type 2 diabetes in older adults are contrary to other reports .
( 19 ) reported a 63% higher risk of type 2 diabetes in the fourth relative to the first quartile of nefa ( rr 1.63 [ 1.04 2.57 ] ) in middle - aged adults .
similar results were noted in the pima study ( 18 ) with a 2.3-fold greater risk of type 2 diabetes comparing the highest with the lowest decile of plasma nefa .
the mean duration of follow - up in our study ( 9.5 years ) was at least twice as long as that reported in the pima study ( 18 ) and nearly five times longer than the 2 years reported in the paris prospective study ( 34 ) .
furthermore , subjects in our study were much older ( mean age 74.8 years ) compared with a mean age of 26 years in the pima study ( 18 ) , 48.9 years for the paris study ( 34 ) , and 52.8 years for atherosclerosis risk in communities ( aric ) study ( 19 ) .
the longer follow - up duration and older age of participants in our cohort might explain the lack of an association in our data .
in particular , it is possible that a single nefa concentration may be less strongly associated with type 2 diabetes risk over long - term follow - up compared with in the short term
. nefa may better predict diabetes risk within a shorter period of follow - up as observed in the paris and pima studies ( 18,34 ) .
this hypothesis is consistent with the larger effect size ( hr 1.63 [ 95% ci 1.072.50 ] comparing the 3rd to the 1st tertile of nefa ) observed in our analysis when follow - up time was restricted to the first 5 years of follow - up .
if this hypothesis is correct , it suggests that it might be necessary to update nefa measurements over time to fully characterize nefa exposure .
nonetheless , our findings also differ from the 53% lower risk of type 2 diabetes ( 95% ci 1973 ) per unit of log nefa observed in the insulin resistance atherosclerosis study ( iras ) ( 20 ) .
iras showed that 2-h glucose was a major confounder ; unfortunately , we did not conduct an oral glucose tolerance test in our cohort at the time of fabp4 and nefa measurement ( 20 ) .
further , iras was multiethnic with younger average age ( 55 vs. 75 years in the chs ) .
what potential biologic mechanisms could causally relate fabp4 and nefa to type 2 diabetes ? as a lipid chaperone , fabp4 is expressed in adipocytes and macrophages and plays an important role in lipid metabolism and perhaps glucose utilization ( 35 ) .
as such , it is possible that fabp4 is a mediator of the obesity  type 2 diabetes association . such a hypothesis would be consistent with the fact that compared with wild - type mice , fabp4 knockout mice do not develop insulin resistance despite extreme adiposity when fed a high - fat diet ( 10 ) . on the other hand , fabp4 might influence the size of fat cells through de novo lipogenesis and lead to obesity . at this point
fabp4 also inhibits stearoyl - coa desaturase-1 , an enzyme that plays a key role in de novo lipogenesis ( 36 ) and could influence plasma nefa . during de
novo lipogenesis , plasma glucose is metabolized to saturated fatty acids ( myristic acid [ c14 ] and palmitic acid [ c16 ] ) ( 37 ) .
stearoyl - coa desaturase-1 catalyzes the conversion of palmitic to palmitoleic acid and stearic ( c18 ) to oleic acid ( c18 ) , a glucose - requiring process ( 36 ) . in fabp4-deficient mice
, there is an increased ratio of short - chain fatty acids ( c14 ) to longer chain ( c18 ) in muscle and adipose tissues ; a more favorable ratio leads to enhanced insulin receptor signaling , amp - activated kinase activity , and insulin - stimulated glucose uptake ( 38 ) .
in addition , fabp4 attenuates the inhibition of hepatic sensitive lipase through its binding of fatty acids ( 17 ) .
hepatic sensitive lipase activity can lead to lipolysis with elevated triglycerides and release of free fatty acids , thus leading to insulin resistance .
higher nefa concentrations can increase insulin resistance ( 21,22 ) , exert toxic effects on pancreatic -cells ( 23,24 ) , and increase glucose production ( 25 ) .
in addition , treatment with pioglitazone ( which reduces insulin resistance ) has been associated with reduced nefa and lipotoxicity ( 39 ) .
additional adjustment for fabp4 did not alter the point estimate for nefa in this study , suggesting that the contribution of fabp4 to nefa concentration may be negligible .
hence , we were unable to account for change in these biomarkers resulting from change in weight or other factors over time .
weight loss is associated with a reduction in serum fabp4 in humans ( 40 ) , and in our study , subjects in the highest tertile of fabp4 were more likely to report unintentional weight loss .
the fact that we observed a stronger association between fabp4 and diabetes risk after exclusion of subjects who reported unintentional weight loss , cancer , or cvd suggests that repeated measures of fabp4 might lead to even stronger relationships .
as an observational study , we can not exclude residual or unmeasured confounding as an alternative explanation of observed associations .
our sample consisted of caucasian and , to a lesser degree , african american adults , all of whom were aged 65 years ; results may not generalize to younger individuals or other race / ethnicities .
we did not have measures of fasting glucose in all years , and , hence , we likely missed type 2 diabetes cases in intervening years .
we did not have 2-h glucose at the time of fabp4 and nefa measurement for further adjustment .
we can not exclude the possibility that obese people were less likely to attend clinic and have their blood glucose measured ; missing data on glucose that was differential based on obesity may have led to an underestimate of type 2 diabetes events .
however , the fact that a similar proportion of obese subjects attended the baseline ( 17.6% ) and 19961997 ( 18.1% ) examination is reassuring . despite these limitations ,
our study has numerous strengths including a large sample size , a representative sample of older adults , inclusion of both men and women , the use of a valid and reproducible method to assess fabp4 and nefa , availability of data on numerous potential confounders , and long - term and nearly complete follow - up . in summary
, we observed a positive association between plasma fabp4 and incident type 2 diabetes that was statistically significant only among lean men .
lastly , our data support a statistically significant association between a single measure of nefa and incident type 2 diabetes in older adults during a shorter but not a longer follow - up period .
 objectiveto examine the relation of fatty acid  binding protein ( fabp)4 and nonesterified fatty acids ( nefas ) to diabetes in older adults.research design and methodswe ascertained incident diabetes among 3,740 cardiovascular health study participants ( 19922007 ) based on the use of hypoglycemic medications , fasting glucose 126 mg / dl , or nonfasting glucose 200 mg / dl . 
 fabp4 and nefa were measured on specimens collected between 1992 and 1993.resultsmean age of the 3,740 subjects studied was 74.8 years . for each sd increase in log fabp4 , 
 hazard ratios ( hrs ) for diabetes were 1.35 ( 95% ci 1.101.65 ) for women and 1.45 ( 1.131.85 ) for men controlling for age , race , education , physical activity , cystatin c , alcohol intake , smoking , self - reported health status , and estrogen use for women ( p for sex - fabp4 interaction 0.10 ) . 
 bmi modified the fabp4-diabetes relation ( p = 0.009 overall ; 0.02 for women and 0.135 for men ) , in that statistically significant higher risk of diabetes was mainly seen in men with bmi < 25 kg / m2 ( hr per sd : 1.78 [ 95% ci 1.132.81 ] ) . 
 there was a modest and nonsignificant association of nefa with diabetes ( ptrend = 0.21 ) . 
 however , when restricted to the first 5 years of follow - up , multivariable - adjusted hrs for diabetes were 1.0 ( ref . ) , 1.68 ( 95% ci 1.122.53 ) , and 1.63 ( 1.072.50 ) across consecutive tertiles of nefa ( ptrend = 0.03).conclusionsplasma fabp4 was positively associated with incident diabetes in older adults , and such association was statistically significant in lean men only . a significant positive association between plasma nefa and incident diabetes 
 was observed during the first 5 years of follow - up . 
RESEARCH DESIGN AND METHODS
Measurement of plasma FABP4 and NEFA
Assessment of incident type 2 diabetes
Other covariates
Statistical analyses
RESULTS
FABP4 and type 2 diabetes risk
NEFA and type 2 diabetes risk
CONCLUSIONS
Supplementary Material