arterial stiffness is increased in patients with type 2 diabetes mellitus ( t2 dm ) , which can potentially increase the risk of morbidity and mortality associated with cardiovascular diseases ( cvd ) .
the brachial - ankle pulse wave velocity ( bapwv ) is a non - invasive technique often used clinically for assessment of arterial wall stiffness and evaluation of the state of atherosclerosis and prediction of cvd in t2 dm patients [ 2 , 3 ] .
previous studies demonstrated that conventional risk factors for cvd , such as age , gender , body mass index ( bmi ) , duration of t2 dm , glycemic control , dyslipidemia , systolic blood pressure ( sbp ) , estimated glomerular filtration rate ( egfr ) , uric acid and albuminuria , are associated with increased arterial stiffness in patients with t2 dm [ 1 , 4 - 6 ] .
however , life style - related problems were not fully taken into consideration in these studies , although the risk of cvd in patients with t2 dm correlates with numerous lifestyle problems [ 7 , 8 ] .
in fact , we recently demonstrated that poor sleep quality in patients with t2 dm correlates with increased arterial stiffness ; however , in that study , we did not take conventional cardiovascular risk factors into full consideration .
another study showed that low physical activity was associated with increased arterial stiffness in newly diagnosed patients with t2 dm . on the other hand ,
the association of other lifestyle habits , such as energy intake , morningness - eveningness , sleep duration and depressive state , with bapwv remains largely unknown in patients with t2 dm . the aim of the present study was to identify lifestyle habits that are associated with bapwv in t2 dm patients free of apparent cvd , using a model adjusted for numerous conventional cardiovascular risk factors and lifestyle habits .
the subjects of this cohort study were recruited from three institutions : the diabetes outpatient clinic of juntendo university ( tokyo , japan ) , naka memorial clinic ( naka , japan ) , and secomedic hospital ( funabashi , japan ) [ 7 , 9 , 10 ] .
the inclusion criteria were as follows : 1 ) male and female t2 dm patients , 2 ) age  25 and < 70 years , and 3 ) signing consent form for participation in the study .
the following exclusion criteria were also applied : 1 ) type 1 or secondary diabetes , 2 ) presence of severe infection , recent surgery , or severe trauma , 3 ) history of myocardial infarction , angina pectoris , or stroke , 4 ) chronic renal failure requiring hemodialysis , 5 ) liver cirrhosis , 6 ) moderate or severe heart failure ( nyha / new york heart association stage iii or higher ) , 7 ) active malignancy , 8) pregnancy , lactation , or possible pregnancy , and 9 ) patients judged as ineligible by the clinical investigators . a total of 1,032 consecutive subjects were screened . between june 2013 and january 2014 , 906 of 1,032 patients who met the above eligibility criteria
were enrolled in this study . among the 906 patients , 736 patients agreed to participate in the study .
the self - administered questionnaire survey to evaluate sleep quality used in the present study was the pittsburgh sleep quality index ( psqi ) [ 9 , 11 ] .
based on the total psqi score , patients were divided into three groups : the  good sleep quality group  with psqi score of  5 ,  average sleep quality group  with psqi 6 - 8 , and  poor sleep quality group  with psqi  9 .
we also used the morning - evening questionnaire ( meq )   to evaluate morningness and eveningness in individuals .
the remaining five questions allowed for choice of time scales and scored from 1 to 5 .
the sum of all scores was converted into three - point meq scales as follows : scores 16 - 52 represented the evening type , scores 53 - 64 represented the neither type , and scores 65 - 86 was considered the morning type , as reported previously .
the participating patients also completed the beck depression inventory ( bdi)-ii , which is a 21-item questionnaire that assesses hopelessness , irritability , cognition , guilt , fatigue , weight loss , and sexual interest , representing depression - related symptoms .
dietary habits during the preceding month were also assessed by the self - administered diet history questionnaire ( bdhq ) .
briefly , the four - page structured bdhq includes questions on selected foods and is designed to estimate the dietary consumption of 56 food and beverage items .
physical activity level was assessed with the four - question international physical activity questionnaire ( ipaq ) , and the results were expressed as metabolic equivalent scores ( metsh / week ) . in the above questionnaires ,
the subjects were also divided into non - smokers , former smokers and current smokers .
blood samples were collected at the outpatient clinic after overnight fast and liver and renal function tests , lipid profile and hba1c ( national glycohemoglobin standardization program ) were measured with standard techniques .
urinary albumin excretion ( uae ) was measured by the latex agglutination assay using a spot urine sample .
the egfr was calculated by the formula : egfr ( ml / min/1.73 m ) = 194  age  serum creatinine (  0.739 for females ) .
bapwv was measured using an automatic waveform analyzer ( bp-203rpe ; colin medical technology , komaki , japan ) , as described previously [ 7 , 9 , 10 ] .
briefly , recording was performed with the patients in the supine position after 5-min rest .
occlusion and monitoring cuffs were placed snugly around both areas in the upper and lower extremities .
the pressure waveforms were then recorded simultaneously from the brachial arteries by the oscillometric method .
all scans were automatically conducted by well - trained investigators who were blinded to the clinical information .
a resting ankle - brachial index of  0.90 was considered to reflect the presence of peripheral artery disease .
the diagnosis of peripheral artery disease based on the ankle - brachial index was further confirmed by computed tomographic angiography , magnetic resonance angiography or catheter angiography .
based on the data obtained from the above procedures , six patients with arterial lumen narrowing of  50% were excluded from analysis .
results were presented as mean  sd or median ( interquartile range : 25 - 75% ) for continuous variables or number ( proportion ) of patients for categorical variables .
multiple linear regression analysis was performed to investigate whether possible cardiovascular risk factors evaluated by clinical , biochemical , metabolic tests and lifestyle habits were associated with bapwv in patients with t2 dm free of apparent cvd .
conventional atherosclerotic risk factors based on clinical judgment and certain life styles were included in the model .
all analyses were performed using the sas software version 9.3 ( sas institute , cary , nc ) .
the subjects of this cohort study were recruited from three institutions : the diabetes outpatient clinic of juntendo university ( tokyo , japan ) , naka memorial clinic ( naka , japan ) , and secomedic hospital ( funabashi , japan ) [ 7 , 9 , 10 ] .
the inclusion criteria were as follows : 1 ) male and female t2 dm patients , 2 ) age  25 and < 70 years , and 3 ) signing consent form for participation in the study .
the following exclusion criteria were also applied : 1 ) type 1 or secondary diabetes , 2 ) presence of severe infection , recent surgery , or severe trauma , 3 ) history of myocardial infarction , angina pectoris , or stroke , 4 ) chronic renal failure requiring hemodialysis , 5 ) liver cirrhosis , 6 ) moderate or severe heart failure ( nyha / new york heart association stage iii or higher ) , 7 ) active malignancy , 8) pregnancy , lactation , or possible pregnancy , and 9 ) patients judged as ineligible by the clinical investigators . a total of 1,032 consecutive subjects were screened . between june 2013 and january 2014 , 906 of 1,032 patients who met the above eligibility criteria
were enrolled in this study . among the 906 patients , 736 patients agreed to participate in the study
the self - administered questionnaire survey to evaluate sleep quality used in the present study was the pittsburgh sleep quality index ( psqi ) [ 9 , 11 ] .
based on the total psqi score , patients were divided into three groups : the  good sleep quality group  with psqi score of  5 ,  average sleep quality group  with psqi 6 - 8 , and  poor sleep quality group  with psqi  9 .
we also used the morning - evening questionnaire ( meq )   to evaluate morningness and eveningness in individuals . briefly , 11 questions allowed for choice and scored from 1 to 4 . two questions allowed for choice and scored 0 , 2 , 4 and 6 .
the remaining five questions allowed for choice of time scales and scored from 1 to 5 .
the sum of all scores was converted into three - point meq scales as follows : scores 16 - 52 represented the evening type , scores 53 - 64 represented the neither type , and scores 65 - 86 was considered the morning type , as reported previously .
the participating patients also completed the beck depression inventory ( bdi)-ii , which is a 21-item questionnaire that assesses hopelessness , irritability , cognition , guilt , fatigue , weight loss , and sexual interest , representing depression - related symptoms .
dietary habits during the preceding month were also assessed by the self - administered diet history questionnaire ( bdhq ) .
briefly , the four - page structured bdhq includes questions on selected foods and is designed to estimate the dietary consumption of 56 food and beverage items .
physical activity level was assessed with the four - question international physical activity questionnaire ( ipaq ) , and the results were expressed as metabolic equivalent scores ( metsh / week ) . in the above questionnaires ,
the subjects were also divided into non - smokers , former smokers and current smokers .
blood samples were collected at the outpatient clinic after overnight fast and liver and renal function tests , lipid profile and hba1c ( national glycohemoglobin standardization program ) were measured with standard techniques .
urinary albumin excretion ( uae ) was measured by the latex agglutination assay using a spot urine sample .
the egfr was calculated by the formula : egfr ( ml / min/1.73 m ) = 194  age  serum creatinine (  0.739 for females ) .
bapwv was measured using an automatic waveform analyzer ( bp-203rpe ; colin medical technology , komaki , japan ) , as described previously [ 7 , 9 , 10 ] .
briefly , recording was performed with the patients in the supine position after 5-min rest .
occlusion and monitoring cuffs were placed snugly around both areas in the upper and lower extremities .
the pressure waveforms were then recorded simultaneously from the brachial arteries by the oscillometric method .
all scans were automatically conducted by well - trained investigators who were blinded to the clinical information .
a resting ankle - brachial index of  0.90 was considered to reflect the presence of peripheral artery disease .
the diagnosis of peripheral artery disease based on the ankle - brachial index was further confirmed by computed tomographic angiography , magnetic resonance angiography or catheter angiography .
based on the data obtained from the above procedures , six patients with arterial lumen narrowing of  50% were excluded from analysis .
results were presented as mean  sd or median ( interquartile range : 25 - 75% ) for continuous variables or number ( proportion ) of patients for categorical variables .
multiple linear regression analysis was performed to investigate whether possible cardiovascular risk factors evaluated by clinical , biochemical , metabolic tests and lifestyle habits were associated with bapwv in patients with t2 dm free of apparent cvd .
conventional atherosclerotic risk factors based on clinical judgment and certain life styles were included in the model .
all analyses were performed using the sas software version 9.3 ( sas institute , cary , nc ) .
among the 736 participating patients , 12 did not complete the questionnaires and/or bapwv measurement and/or had an ankle - brachial index of  0.90 , and accordingly were excluded from analysis .
table 1 summarizes the characteristics of the remaining 724 japanese patients with t2 dm . the mean age was 57.8  8.6 years , and 62.8% of the subjects were males .
the mean hba1c was 7.01.0% , and the estimated duration of t2 dm was 9.9  7.2 years .
most subjects had attended educational programs in the past about diet and exercise therapy and received appropriate medical treatments .
alt : alanine aminotransferase ; ast : aspartate aminotransferase ; bapwv : brachial - ankle pulse wave velocity ; egfr : estimated glomerular filtration rate ; hdl - c : high - density lipoprotein - cholesterol ; uae : urinary albumin excretion ; -gtp : -glutamyl transpeptidase .
the results of multivariable linear regression analysis are shown in table 2 . the regression analysis that included age and gender , which are major confounding factors for atherosclerosis , demonstrated that age and male sex were positively associated with bapwv ( model 1 ) . in model 2 adjusted for conventional cardiovascular risk factors
( + model 1 ) , age , duration of t2 dm , hba1c , sbp , uric acid and uae were positively associated with bapwv while bmi was negatively associated with bapwv .
almost similar findings were observed in model 3 adjusted for alcohol consumption , smoking , and background therapies for cvd risk factors ( + model 2 ) . in model 4 adjusted for lifestyle habits ( + model 3 ) , age , duration of t2 dm , sbp , uric acid , uae and poor sleep quality were positively associated with bapwv while bmi was negatively associated with bapwv .
multiple linear regression analysis included age and gender ( model 1 ) , model 1 plus body mass index , estimated duration of diabetes , hba1c , systolic blood pressure , diastolic blood pressure , total cholesterol , high density lipoprotein - cholesterol , triglyceride , ast , alt , -gtp , serum uric acid , egfr and uae ( model 2 ) , model 2 plus current smoker , alcohol , diabetic retinopathy , insulin therapy , hypertension medication , hyperlipidemia medication and anti - platelet agents ( model 3 ) , model 3 plus morningness - eveningness questionnaire , pittsburgh sleep quality index , beck depression inventory - ii , energy intake ( kcal / day ) , physical activity ( kcal / day ) and sleep time ( model 4 ) .
est : standardized estimate of regression parameter ; alt : alanine aminotransferase ; ast : aspartate aminotransferase ; bapwv : brachial - ankle pulse wave velocity ; egfr : estimated glomerular filtration rate ; hdl - c : high - density lipoprotein - cholesterol ; uae : urinary albumin excretion ; -gtp : -glutamyl transpeptidase .
in agreement with previous studies [ 1 , 4 - 6 , 20 ] , our data demonstrated that conventional cardiovascular risk factors , such as age , duration of t2 dm , sbp , uric acid and uae , were associated with increased arterial stiffness in patients with t2 dm even after adjustment for some lifestyle habits .
furthermore , we found that poor sleep quality was associated with arterial stiffness even after adjustment for several conventional cardiovascular risk factors and other lifestyle habits . in this regard
, a previous report demonstrated that high levels of catecholamines caused by poor sleep quality may be associated with progression of arterial stiffness in healthy middle - aged adults .
high catecholamine levels could promote smooth muscle cell proliferation and fibrosis , leading to structural changes in the arterial wall .
although the study design does not allow evaluation of causal relations , the above data suggest that poor sleep quality may be an important target of interventions that can prevent arterial stiffness in patients with t2 dm . in contrast
, our data failed to show close association of other lifestyle problems , such as energy intake , physical activity , morningness - eveningness , sleep duration and depressive state , with arterial stiffness in patients with t2 dm .
a recent clinical trial demonstrated that life style interventions , with a special focus on reduced calorie intake and increased physical activity , did not affect the rate of cvd in obese t2 dm patients .
it is possible that not only caloric intake , but rather dietary composition , may need to be modified to prevent or delay the development of cvd in patients with t2 dm .
while previous reports demonstrated that bmi was positively associated with arterial stiffness [ 5 , 20 , 24 , 25 ] , bmi was inversely associated with arterial stiffness in this study , consistent with a previous report in non - t2 dm patients .
the exact explanation for the conflicting results is unknown ; however , a previous study showed higher bapwv levels in t2 dm patients with normal bmi and increased visceral adiposity compared to those with higher bmi and normal visceral adiposity .
generally , increased visceral adiposity is associated with insulin resistance , which increases the production of inflammatory cytokines , leading to arterial stiffness .
since asians tend to have insulin resistance even with normal bmi , evaluation of visceral adiposity may be helpful in the assessment of effect of obesity on arterial stiffness in these subjects .
a close association between serum uric acid and arterial stiffness in male patients with newly diagnosed t2 dm was reported previously , even after adjustment for several risk factors for atherosclerosis . in the present study
, we demonstrated a significant association between serum uric acid and arterial stiffness in a wider range of t2 dm population than the above study , even after adjustment for lifestyle habits in addition to numerous cardiovascular risk factors .
however , whether serum uric acid plays an important role or is a potentially useful sensitive marker for identifying patients at high risk for cvd is not clear in this cross - sectional study .
indeed , the deleterious effect of hyperuricemia on arterial stiffness may be mediated through other interactive cardiovascular risk factors and/or the effect of hyperuricemia may depend on the stage of atherosclerosis [ 6 , 29 ] .
first , the cross - sectional design does not allow evaluation of the causal relationship between risk factors for atherosclerosis and arterial stiffness .
third , we can not rule out the possible effects of other lifestyle habits that we did not assessed in this study on arterial stiffness . in conclusion
, we found that several conventional cardiovascular risk factors , such as age , duration of t2 dm , sbp , serum uric acid , uae , lower bmi and poor sleep quality were associated with bapwv even after adjustment for multiple traditional cardiovascular risk factors and lifestyle habits .
in conclusion , we found that several conventional cardiovascular risk factors , such as age , duration of t2 dm , sbp , serum uric acid , uae , lower bmi and poor sleep quality were associated with bapwv even after adjustment for multiple traditional cardiovascular risk factors and lifestyle habits .
the study was approved by the institutional review board of our hospital and conducted in accordance with the principles described in the declaration of helsinki .
all patients provided written informed consent before participation and registered on the university hospital medical information network clinical trials registry ( umin000010932 ) .
hm is an employee of takeda pharmaceutical co. hw has received lecture fees from novo nordisk , inc . ,
eli lilly and company , sanofi , dainippon sumitomo pharma co. , fujifilm , bayer health care , kissei pharmaceutical company , mochida pharmaceutical company , msd , takeda pharmaceutical company , boehringer ingelheim pharmaceuticals , inc .
, daiichi - sankyo , ono pharmaceutical co. , ltd , novartis pharmaceuticals corporation , mitsubishi tanabe pharma corporation , astrazeneca lp , kyowa hakko kirin company , ltd , sanwa kagaku kenkyusyo company , ltd , kowa company ltd , astellas pharma , inc .
, advisory fees from novo nordisk , inc . , mochida pharma company , astrazeneca lp , kowa company , astellas pharma , inc . ,
msd , mitsubishi tanabe pharma corporation , novartis pharmaceuticals corporation , dainippon sumitomo pharma co. , takeda pharmaceutical company , ono pharmaceutical co. , pfizer , inc . ,
kowa company and research funds from boehringer ingelheim , pfizer , mochida pharmaceutical co. , sanofi - aventis , novo nordisk pharma , novartis pharmaceuticals , sanwakagaku kenkyusho , terumo corp .
, takeda pharmaceutical co. , msd , shionogi , pharma , dainippon sumitomo pharma , kissei pharma , and astrazeneca .
all authors contributed to the study design and were involved at all stages of manuscript development .
all authors were also involved in the collection , analysis and interpretation of data , reviewed / edited the manuscript and approved the final manuscript .
hw is the principal guarantors of this work and has full access to all study data and takes responsibility for the integrity of the data and accuracy of data analysis .
this study was conducted through a research grant from the manpei suzuki diabetes foundation ( to tm ) .
the funding agency had no role in the study design , data collection or analysis , decision to publish , or preparation of the manuscript .
alanine aminotransferase brachial - ankle pulse wave velocity brief , self - administered diet history questionnaire beck depression inventory systolic blood pressure cardiovascular disease estimated glomerular filtration rate -glutamyl transpeptidase high - density lipoprotein - cholesterol international physical activity questionnaire morningness - eveningness questionnaire pittsburgh sleep quality index type 2 diabetes mellitus urinary albumin excretion
 backgroundwhile conventional cardiovascular risk factors and certain lifestyle habits are associated with arterial stiffness in patients with type 2 diabetes mellitus ( t2 dm ) , it is still unknown whether they are actually associated with arterial stiffness even after adjustment for conventional cardiovascular risk factors and lifestyle habits . 
 the aim of this study was to identify variables that are associated with brachial - ankle pulse wave velocity ( bapwv).methodsthe study participants comprised 724 japanese t2 dm outpatients free of history of cardiovascular diseases . 
 lifestyle habits were analyzed using self - reported questionnaires . 
 the associations among conventional cardiovascular risk factors and lifestyle habits with bapwv were investigated by multivariable linear regression analysis.resultsthe mean age of the study subjects was 57.8  8.6 years , and 62.8% of those were males . 
 the mean hba1c was 7.01.0% , and the estimated duration of t2 dm was 9.9  7.2 years . 
 multiple linear regression analysis that included age and gender demonstrated that age and male sex were positively associated with bapwv . in a model adjusted for numerous conventional cardiovascular risk factors and lifestyle habits , age , duration of t2 dm , systolic blood pressure , serum uric acid , urinary albumin excretion and poor sleep quality 
 were positively associated with bapwv , while body mass index was negatively associated with bapwv.conclusionsin japanese t2 dm , in addition to several conventional cardiovascular risk factors , poor sleep quality was associated with bapwv even after adjustment for numerous conventional cardiovascular risk factors and lifestyle habits . 
Introduction
Materials and Methods
Subjects
Questionnaire survey
Blood and urine tests
Measurement of baPWV
Statistical analysis
Results
Discussion
Conclusion
Declarations
Competing Interests
Author Contributions
Grant Support
Abbreviations