the study was funded by the american diabetes association and approved by the university of minnesota institutional review board . we recruited participants between january 2007 and march 2009 from clinics and communities in the twin cities metro area of minnesota . patients were either referred to the study by their physicians or self - referred from flyers distributed at health fairs , community centers , and churches ; media advertisements ; word of mouth ; or postcards . the study included men and women aged 40 years and older with a diagnosis of pad ( resting or postexercise ankle - brachial index [ abi ] of < 0.90 , toe - brachial index 0.7 ( 9 ) , or prior surgery for pad with continued exertional leg symptoms not including joint pain ) ; a diagnosis of dm type i or ii ( medical history of medication use or diet control for hyperglycemia ) ; and leg symptoms at enrollment ( as captured by the san diego claudication questionnaire ) ( 10 ) . additionally , we excluded anyone who indicated  no intention to start exercising in the next 6 months .  by excluding these individuals , we focused on determining the effectiveness of our intervention at improving functional outcomes versus motivating very sedentary patients . we excluded participants with no available phone , foot or lower leg amputation , critical leg ischemia , or lower extremity revascularization within 6 months before enrollment . because of possible adverse consequences of exercise , we excluded patients with a myocardial infarction within the preceding 3 months ; evidence of significant coronary ischemia at a low workload as determined by exercise treadmill testing ; systolic blood pressure greater than 180 mmhg or diastolic pressure greater than 110 mmhg ; diagnosis of a life - threatening malignancy within the past year ; or exercise tolerance limited by leg pain of nonvascular origin or other factors such as arthritis , dyspnea , dizziness , angina class 2 or higher , and chronic obstructive pulmonary disease . research staff assessed medical history and administered the san diego claudication questionnaire . additionally , staff administered the physical activity readiness questionnaire ( par - q ) , a 7-item questionnaire that detects signs and symptoms that contraindicate exercise ( 11 ) . eligibility was confirmed with treadmill testing ( described below ) and abi measurements as described previously ( 8) . for people with an abi > 1.3 , indicating arterial calcification , we obtained toe - brachial indexes ( 9 ) . great toe pressures were obtained with a toe cuff and photoplethysmography ( summit doppler vista avs 2007 ) to detect the systolic pressure at which blood flow returned . eligible individuals were randomized to intervention or control using permuted blocks with randomized block sizes 2 , 4 , 6 , or 8 to ensure equal numbers in both groups . outcomes were analyzed according to the randomized allocation ( intention - to - treat ) . all participants viewed a 7-min educational video about pad and its clinical leg symptoms , life - threatening consequences of pad ( heart attack and stroke ) , other adverse outcomes ( walking disability ) , and strategies for disease and risk factor management ( smoking cessation , weight control , aerobic activity ) . after the video , each participant met face - to - face with the research coordinator . the coordinator queried participants regarding self - management behaviors ( i.e. , glucose monitoring , blood pressure monitoring ) and gave them a calendar in which to document their daily glucose results , weekly blood pressures , and any routine lipid results provided by their primary care physician . participants received parking vouchers for each visit and $ 30 for each of the 3- and 6-month assessment visits . intervention group subjects participated in a home - based walking program with three components : 1 ) a one - on - one interaction with the research coordinator at baseline ; 2 ) walking training and weekly group walking classes with an instructor ; and 3 ) biweekly telephone calls for 6 months . for the baseline interaction , discussion focused on the participant s current stage of change ( 12 ) , as determined from his or her responses to part 1 of the patient - centered assessment and counseling for exercise ( pace ) protocol ( e.g. , i ve been doing vigorous exercise 3 or more days per week for the last 6 months or more for this study , we modified the original pace assessment and counseling treatment manual ( 13 ) to address the specific walking recommendations for patients with pad , rather than any form of exercise . the participant then completed part 2 of the pace protocol ( one of three possible instruments depending on the score in part 1 ) to better define specific factors that facilitate adherence to routine exercise ( walking ) . for example , individuals with a pace score of 24 were asked to write down the two main benefits they hoped to gain from being active and were asked to make a physical activity plan and check off roadblocks to routine exercise via walking ( e.g. , the coordinator reviewed each participant s plans for walking routinely and discussed how to overcome roadblocks . after the baseline visit , participants were scheduled to complete two 1-h walking training sessions , led by an experienced exercise instructor . sessions were held at the university of minnesota or another location suitable for walking ( e.g. , a park ) . the exercise instructor asked participants to describe what they hoped to gain from walking for exercise . session two was a practice walking session with the exercise instructor and one or more participants . for this session , participants listened to an audiotaped instructional aid developed by the american heart association . participants were then encouraged to walk 1 day per week with the study exercise instructor and other participants , as available , and to continue walking on their own at least 3 days per week for a minimum of 4 days of walking each week ; participants were advised to walk 50 min total for each session and , using their pedometers , to increase the number of steps by 50 each session . , intervention participants completed the pace assessment and the exercise behaviors questionnaire ( described below ) ( 15 ) and discussed their strategies for atherosclerotic risk factor control and adherence to walking during the past 2 weeks . individuals randomized to the attention control group participated in twice - monthly phone calls with the research coordinator . during these 10- to 15-min calls , control group participants shared and discussed the information documented in their calendars on blood glucose , blood pressure , and cholesterol levels ( if available ) and their smoking habits , if applicable . it has a summary -statistic for reliability of 0.81 ( 95% confidence interval [ ci ] 0.78 , 0.84 ) and a summary -statistic for validity of 0.58 ( 95% ci 0.52 , 0.64 ) ( 16 ) . the primary outcome was change from baseline to 6 months in mean maximal treadmill walking distance , determined from using the gardner - skinner graded exercise treadmill test with electrocardiographic monitoring ( 17 ) . secondary outcomes were change from baseline to 3 months in mean maximal treadmill walking distance and changes from baseline to 3 and 6 months in the measures listed below . we captured the participant s ability to walk in the community ( i.e. , lower limb function ) using the validated interviewer - administered walking impairment questionnaire ( 18 ) . this survey captures three domains : walking distance , walking speed , and stair - climbing capacity . the domains are scored on 0 to 100 scales , 0 representing complete inability to perform the task and 100 representing no limitations in walking short and long distances , walking at a fast pace , and climbing three flights of stairs . health - related quality of life was measured using the medical outcomes study ( mos ) short form survey ( sf-36 ) ( 19 ) . each subscale is scored from 0 to 100 ; higher scores indicate more positive quality of life . depressive symptoms , which are associated with walking impairment in patients with pad ( 20 ) , were measured using the geriatric depression score , a 15-item screening instrument . we measured self - efficacy  self - confidence to perform certain activities to manage their disease  using the six - item self - efficacy for managing chronic disease scale ( 21 ) . the association of self - efficacy with walking ability , measured in these patients at baseline , is reported elsewhere ( 22 ) . we administered the stanford patient education research center exercise behavior survey during each follow - up phone call . the exercise behaviors survey is a six - item instrument with questions regarding the type of activity and the length of time during which the patient engaged in that activity during the past week ( 23 ) . during each biweekly phone call , study staff asked whether the patient had developed chest pain , shortness of breath , or any symptoms requiring hospitalization in the past 2 weeks . if the participant responded yes , he / she was asked about diagnostic testing , final diagnosis , and whether the hospital physician stated the participant could continue in the study . the study staff also ascertained leg symptoms , testing for pad ( e.g. , angiography ) , or invasive therapy for pad . intervention and control groups were compared according to baseline characteristics using fisher s exact tests for categorical variables and t tests ( two - sided ) for continuous variables . analyses were done using sas ( v. 9.1.3 ; sas institute , cary , nc ) . the treatment groups were compared according to change from baseline to 6- and 3-month follow - up using the same tests . as a check for selection bias from dropouts , we performed longitudinal analyses of four outcomes , the primary outcome and three secondary outcomes of particular interest : treadmill walking distance , walking speed from the walking impairment questionnaire , and the physical and mental health aggregates of sf-36 . the analysis used a mixed linear model , including up to 3 cases per participant ( baseline , 3 months , 6 months ) , using all available data . treatment groups were compared according to change from baseline to the average of the 3- and 6-month visits , an average treatment effect over the two follow - ups . the longitudinal results were very similar to the simpler comparisons of changes by the 3- and 6-month visits and are reported briefly . a priori , 64 patients per arm gave 80% power to detect a moderate standardized effect size of 0.50 ( a difference between groups of 0.06 miles in average change in treadmill walking distance ) . we recruited participants between january 2007 and march 2009 from clinics and communities in the twin cities metro area of minnesota . patients were either referred to the study by their physicians or self - referred from flyers distributed at health fairs , community centers , and churches ; media advertisements ; word of mouth ; or postcards . the study included men and women aged 40 years and older with a diagnosis of pad ( resting or postexercise ankle - brachial index [ abi ] of < 0.90 , toe - brachial index 0.7 ( 9 ) , or prior surgery for pad with continued exertional leg symptoms not including joint pain ) ; a diagnosis of dm type i or ii ( medical history of medication use or diet control for hyperglycemia ) ; and leg symptoms at enrollment ( as captured by the san diego claudication questionnaire ) ( 10 ) . additionally , we excluded anyone who indicated  no intention to start exercising in the next 6 months .  by excluding these individuals , we focused on determining the effectiveness of our intervention at improving functional outcomes versus motivating very sedentary patients . we excluded participants with no available phone , foot or lower leg amputation , critical leg ischemia , or lower extremity revascularization within 6 months before enrollment . because of possible adverse consequences of exercise , we excluded patients with a myocardial infarction within the preceding 3 months ; evidence of significant coronary ischemia at a low workload as determined by exercise treadmill testing ; systolic blood pressure greater than 180 mmhg or diastolic pressure greater than 110 mmhg ; diagnosis of a life - threatening malignancy within the past year ; or exercise tolerance limited by leg pain of nonvascular origin or other factors such as arthritis , dyspnea , dizziness , angina class 2 or higher , and chronic obstructive pulmonary disease . research staff assessed medical history and administered the san diego claudication questionnaire . additionally , staff administered the physical activity readiness questionnaire ( par - q ) , a 7-item questionnaire that detects signs and symptoms that contraindicate exercise ( 11 ) . eligibility was confirmed with treadmill testing ( described below ) and abi measurements as described previously ( 8) . for people with an abi > 1.3 , indicating arterial calcification , we obtained toe - brachial indexes ( 9 ) . great toe pressures were obtained with a toe cuff and photoplethysmography ( summit doppler vista avs 2007 ) to detect the systolic pressure at which blood flow returned . eligible individuals were randomized to intervention or control using permuted blocks with randomized block sizes 2 , 4 , 6 , or 8 to ensure equal numbers in both groups . outcomes were analyzed according to the randomized allocation ( intention - to - treat ) . all participants viewed a 7-min educational video about pad and its clinical leg symptoms , life - threatening consequences of pad ( heart attack and stroke ) , other adverse outcomes ( walking disability ) , and strategies for disease and risk factor management ( smoking cessation , weight control , aerobic activity ) . after the video , each participant met face - to - face with the research coordinator . the coordinator queried participants regarding self - management behaviors ( i.e. , glucose monitoring , blood pressure monitoring ) and gave them a calendar in which to document their daily glucose results , weekly blood pressures , and any routine lipid results provided by their primary care physician . participants received parking vouchers for each visit and $ 30 for each of the 3- and 6-month assessment visits . intervention group subjects participated in a home - based walking program with three components : 1 ) a one - on - one interaction with the research coordinator at baseline ; 2 ) walking training and weekly group walking classes with an instructor ; and 3 ) biweekly telephone calls for 6 months . for the baseline interaction , discussion focused on the participant s current stage of change ( 12 ) , as determined from his or her responses to part 1 of the patient - centered assessment and counseling for exercise ( pace ) protocol ( e.g. , i have been thinking of starting to exercise in the next 6 months  = 2 ; i ve been doing vigorous exercise 3 or more days per week for the last 6 months or more for this study , we modified the original pace assessment and counseling treatment manual ( 13 ) to address the specific walking recommendations for patients with pad , rather than any form of exercise . the participant then completed part 2 of the pace protocol ( one of three possible instruments depending on the score in part 1 ) to better define specific factors that facilitate adherence to routine exercise ( walking ) . for example , individuals with a pace score of 24 were asked to write down the two main benefits they hoped to gain from being active and were asked to make a physical activity plan and check off roadblocks to routine exercise via walking ( e.g. , the coordinator reviewed each participant s plans for walking routinely and discussed how to overcome roadblocks . after the baseline visit , participants were scheduled to complete two 1-h walking training sessions , led by an experienced exercise instructor . sessions were held at the university of minnesota or another location suitable for walking ( e.g. , a park ) . the exercise instructor asked participants to describe what they hoped to gain from walking for exercise . session two was a practice walking session with the exercise instructor and one or more participants . for this session , participants listened to an audiotaped instructional aid developed by the american heart association . participants were then encouraged to walk 1 day per week with the study exercise instructor and other participants , as available , and to continue walking on their own at least 3 days per week for a minimum of 4 days of walking each week ; participants were advised to walk 50 min total for each session and , using their pedometers , to increase the number of steps by 50 each session . , intervention participants completed the pace assessment and the exercise behaviors questionnaire ( described below ) ( 15 ) and discussed their strategies for atherosclerotic risk factor control and adherence to walking during the past 2 weeks . individuals randomized to the attention control group participated in twice - monthly phone calls with the research coordinator . during these 10- to 15-min calls , control group participants shared and discussed the information documented in their calendars on blood glucose , blood pressure , and cholesterol levels ( if available ) and their smoking habits , if applicable . at baseline only , the lifestyle and clinical survey was administered to ascertain sociodemographics and comorbidities . it has a summary -statistic for reliability of 0.81 ( 95% confidence interval [ ci ] 0.78 , 0.84 ) and a summary -statistic for validity of 0.58 ( 95% ci 0.52 , 0.64 ) ( 16 ) . the primary outcome was change from baseline to 6 months in mean maximal treadmill walking distance , determined from using the gardner - skinner graded exercise treadmill test with electrocardiographic monitoring ( 17 ) . secondary outcomes were change from baseline to 3 months in mean maximal treadmill walking distance and changes from baseline to 3 and 6 months in the measures listed below . we captured the participant s ability to walk in the community ( i.e. , lower limb function ) using the validated interviewer - administered walking impairment questionnaire ( 18 ) . this survey captures three domains : walking distance , walking speed , and stair - climbing capacity . the domains are scored on 0 to 100 scales , 0 representing complete inability to perform the task and 100 representing no limitations in walking short and long distances , walking at a fast pace , and climbing three flights of stairs . health - related quality of life was measured using the medical outcomes study ( mos ) short form survey ( sf-36 ) ( 19 ) . each subscale is scored from 0 to 100 ; higher scores indicate more positive quality of life . depressive symptoms , which are associated with walking impairment in patients with pad ( 20 ) , were measured using the geriatric depression score , a 15-item screening instrument . we measured self - efficacy  self - confidence to perform certain activities to manage their disease  using the six - item self - efficacy for managing chronic disease scale ( 21 ) . the association of self - efficacy with walking ability , measured in these patients at baseline , is reported elsewhere ( 22 ) . we administered the stanford patient education research center exercise behavior survey during each follow - up phone call . the exercise behaviors survey is a six - item instrument with questions regarding the type of activity and the length of time during which the patient engaged in that activity during the past week ( 23 ) . we captured the participant s ability to walk in the community ( i.e. , lower limb function ) using the validated interviewer - administered walking impairment questionnaire ( 18 ) . this survey captures three domains : walking distance , walking speed , and stair - climbing capacity . the domains are scored on 0 to 100 scales , 0 representing complete inability to perform the task and 100 representing no limitations in walking short and long distances , walking at a fast pace , and climbing three flights of stairs . health - related quality of life was measured using the medical outcomes study ( mos ) short form survey ( sf-36 ) ( 19 ) . each subscale is scored from 0 to 100 ; higher scores indicate more positive quality of life . depressive symptoms , which are associated with walking impairment in patients with pad ( 20 ) , were measured using the geriatric depression score , a 15-item screening instrument . we measured self - efficacy  self - confidence to perform certain activities to manage their disease  using the six - item self - efficacy for managing chronic disease scale ( 21 ) . the association of self - efficacy with walking ability , measured in these patients at baseline , is reported elsewhere ( 22 ) . we administered the stanford patient education research center exercise behavior survey during each follow - up phone call . the exercise behaviors survey is a six - item instrument with questions regarding the type of activity and the length of time during which the patient engaged in that activity during the past week ( 23 ) . during each biweekly phone call , study staff asked whether the patient had developed chest pain , shortness of breath , or any symptoms requiring hospitalization in the past 2 weeks . if the participant responded yes , he / she was asked about diagnostic testing , final diagnosis , and whether the hospital physician stated the participant could continue in the study . the study staff also ascertained leg symptoms , testing for pad ( e.g. , angiography ) , or invasive therapy for pad . intervention and control groups were compared according to baseline characteristics using fisher s exact tests for categorical variables and t tests ( two - sided ) for continuous variables . analyses were done using sas ( v. 9.1.3 ; sas institute , cary , nc ) . the treatment groups were compared according to change from baseline to 6- and 3-month follow - up using the same tests . as a check for selection bias from dropouts , we performed longitudinal analyses of four outcomes , the primary outcome and three secondary outcomes of particular interest : treadmill walking distance , walking speed from the walking impairment questionnaire , and the physical and mental health aggregates of sf-36 . the analysis used a mixed linear model , including up to 3 cases per participant ( baseline , 3 months , 6 months ) , using all available data . treatment groups were compared according to change from baseline to the average of the 3- and 6-month visits , an average treatment effect over the two follow - ups . the longitudinal results were very similar to the simpler comparisons of changes by the 3- and 6-month visits and are reported briefly . a priori , 64 patients per arm gave 80% power to detect a moderate standardized effect size of 0.50 ( a difference between groups of 0.06 miles in average change in treadmill walking distance ) . 1 ) . of the 462 eligible for an in - person visit , we excluded 371 for lack of objective evidence of pad or inability to complete treadmill testing . we enrolled 145 participants ; 19 ( 13.1% ) provided no treadmill outcome measures at the 6-month follow - up visit . atherosclerotic risk factors were common : 106 ( 73% ) participants were former or current smokers and 119 ( 82% ) had hypertension . at baseline , 19 ( 26% ) baseline characteristics by randomized group for the baseline outcome measures , data are mean ( sd ) . * fisher s exact test for categorical variables and t tests for continuous variables ; * * two answered more than one category ; t tests comparing means of the two randomized groups ;  physical functioning , role - physical , bodily pain , general health , vitality , social functioning , role - emotional , and mental health are captured by the mos sf-36 . overall , subjects walked a mean distance of 448 m ( sd 237.1 ) on the treadmill at baseline . considering changes from baseline to 6 months ( table 2 ) , intervention and control groups did not differ significantly in the primary outcome , change in maximal treadmill walking distance ( average [ se ] change : control 39.2 [ 19.6 ] meters , intervention 24.5 [ 19.6 ] ; p = 0.60 ) , or change in treadmill walking distance until onset of pain ( average [ se ] change : control 52.3 [ 23.6 ] meters , intervention 66.7 [ 21.0 ] ; p = 0.65 ) . the intervention group had greater improvement than control subjects in two secondary outcomes , walking speed and mental health . the intervention group 's average walking speed improved by 5.7 ( 2.2 ) percentage points , whereas the control group 's average score decreased by 1.9 ( 2.8 ) percentage points ( p = 0.034 ) ; and the intervention group 's mental - health average score improved by 3.2 ( 1.5 ) units , compared with a decrease of 2.4 ( 1.5 ) units for the control group ( p = 0.01 ) . there was a nonsignificant trend toward greater improvement in quality of life ( i.e. , physical functioning and role - emotional ) for the intervention group compared with the control group . comparison of intervention and control groups and change from baseline to 6 months * p value from a t test ;  physical functioning , role - physical , bodily pain , general health , vitality , social functioning , role - emotional , and mental health are captured by the mos sf-36 . results from the longitudinal analyses differed little from those in the simple analyses of change to 6- and 3-month follow - up . for example , in the longitudinal analysis of walking speed , the intervention group improved by 7.6 units more than the control group ( se 3.0 , p = 0.013 ; compare with table 2 ) . for our primary outcome , the effect of study treatment differed depending on whether the subjects were taking claudication medication at baseline ( p = 0.0025 in a test of the interaction ) ; overall , the study groups did not differ significantly in the primary outcome of maximal treadmill walking distance after adjusting for baseline use of claudication medication ( p = 0.074 ) . additionally , there were no significant differences between study groups in 3 or 6-month changes in walking speed , physical functioning , mental health , physical component summary score , or mental component summary score after adjusting for baseline use of claudication medication . we have presented results from the first large - scale trial of a home - based walking intervention for people with dm and pad . a 6-month home - based walking program did not improve the primary outcome of 6-month change in maximal treadmill walking distance compared with control . however , the 6-month home - based walking program did improve some secondary outcomes , specifically walking speed and 6-month physical functioning and mental health ( i.e. , role - emotional ) . these results suggest that home - based walking holds promise for improving walking speed and quality of life in people with dm and pad . earlier studies of walking interventions in pad demonstrated improvement in walking speed , but they were based on supervised treadmill walking interventions ( 24,25 ) . our intervention was home - based , with one weekly group walking class , and can be easily implemented in clinical practice . an additional benefit of our intervention was improvement in mental health per the sf-36 quality of life measure . prior trials ( 24,25 ) showed improved quality of life for people with pad who completed a supervised treadmill walking program . we add to these prior studies by showing improved quality of life for people with pad randomized to a 6-month home - based walking intervention . both physical and role - emotional functioning were improved for people randomized to the intervention . although these improvements were not statistically significant , the changes highlight the need for development of more robust home - based walking interventions in future trials targeting people with pad . when comparing intervention to control , there were trends toward benefit for several outcome measures including time to onset of pain , walking impairment parameters ( i.e. , distance , stair climbing ) , all quality of life subscale scores , and exercise behaviors . we found no differences between the intervention and control groups on changes from baseline to 6 months in the outcomes of self - efficacy or depressive symptoms . we did find an association of self - efficacy with walking ability at baseline ( 22 ) , but the final results from the trial suggest that our intervention did not affect self - efficacy . strengths of this study include a 6-month intervention focused on home - based walking and patients with diabetes with pad and either intermittent claudication or atypical leg symptoms . this latter group , people with dm and pad with atypical leg symptoms , is often underrepresented in exercise trials for pad . an additional strength of this study was the translation of an intervention initially developed for a primary - care clinical setting ( i.e. , pace ) into a community - based intervention to promote home - based walking in a high - risk population . limitations of the study include possible contamination of the attention control group , since the counselors were the same for both groups . additionally , over 90% of participants enrolled in the study because they hoped to increase their walking . this was discovered in a close - out survey in which participants were asked about their perceptions of the study and whether enrolling in the study motivated them to walk . this finding highlights the need to carefully develop recruitment materials so the focus of intervention is not so apparent as to lead to participation bias . we used various methods to increase minority participation ( e.g. , announcements on radio stations in which listening audiences were largely minorities , attendance at churches in which members were minorities ) but , given that most study assessments required visiting the university and people in the community were not as willing to do that , less than 10% of our participants were ethnic minorities . finally , at baseline , control participants were more likely to use claudication medication than intervention participants . this could have influenced the trend toward a greater change in the primary outcome for control as compared with intervention participants . our study is the first large - scale walking intervention trial in pad to use home - based walking versus an attention control . we demonstrated that a home - based walking program can be used in patients with dm and pad . such a program may improve walking speed and quality of life in this high - risk population .