type 2 diabetes mellitus ( t2 dm ) is one of the most common metabolic diseases worldwide . it 
 is characterized by the impaired secretion or action of insulin and subsequent 
 hyperglycemia1 . people with t2 dm often 
 complain of fatigue and exhibit limitations of bodily functions2 . this can profoundly affect a person s engagement in 
 activities of daily living and reduce quality of life . t2 dm can be treated with medications , 
 with or without insulin , but it requires a multi - disciplinary approach . an active lifestyle , 
 proper weight management , good nutrition , and avoidance of tobacco use can prevent or delay 
 the onset and development of t2dm3 . appropriate physical exercise , in addition to diet modification and medications , has been 
 recommended as one of the three main components of diabetic management4 . there is some evidence supporting the benefits of exercise 
 performed by individuals with t2 dm , such as aerobic exercise and resistance training5 , 6 . however , patients with t2 dm are often extremely frail and unmotivated , which leads to poor 
 compliance with physical training . whole - body vibration ( wbv ) , a new physical therapeutic modality , was initially developed 
 for use in the training of elite athletes . now , there are numerous studies about the 
 influence of wbv on different population subsets , such as patients with cerebrovascular 
 accidents7 , 8 , chronic obstructive pulmonary diseases9 , and osteoarthritis10 . these studies have revealed that wbv may have positive effects on 
 physical functions , like mobility and balance . the effect of wbv is thought to be mediated 
 by muscle contraction , facilitation of sensory inputs , and stimulation of proprioceptive 
 receptors11 . in recent years , an 
 increasing number of studies have examined whether or not wbv is truly beneficial for people 
 with t2dm12,13,14,15,16,17,18,19 , but the evidence still shows inconsistencies . the aim of this 
 review was to systematically assess randomized controlled trials featuring the application 
 of wbv aiming to improve the physical function of people with t2 dm . a literature search for relevant studies was conducted on medline ( 1966 to jul 2015 ; via 
 ovid ) , the cochrane central register of controlled trials ( central ) ( the cochrane library , 
 issue 7 of 12 jul 2015 ) , pubmed ( 1966 to jul 2015 ) , physiotherapy evidence database ( pedro ) 
 ( 1929 to jul 2015 ; via website ) , and embase ( 1980 to jul 2015 ; via ovid ) . the keywords used 
 for searching were diabetes mellitus or diabetes or dm and vibration or whole body vibration 
 or wbv or biomechanical stimulation and randomized controlled trial or clinical trial or 
 controlled clinical trial or trial or randomized or randomly or placebo . the reference lists 
 of each selected article were manually searched to identify other potentially relevant 
 papers . the latest search was performed on 18th december , 2015 , on pubmed to update the 
 study . studies that met the requirements using the following criteria were considered for 
 review : ( 1 ) randomized controlled trials ( rcts ) concerning the effect of wbv , with or 
 without physical activity , on people diagnosed with t2 dm ; ( 2 ) publication in english ; ( 3 ) 
 wbv aiming improve the physical function ( e.g. mobility ) of people with t2 dm ; and ( 4 ) the 
 intervention in the control arm of the study included a sham wbv intervention , exercise , or 
 other conventional treatment modalities . articles were excluded if they were : ( 1 ) studies 
 conducted on patients with other primary diagnoses ( e.g. stroke ) ; ( 2 ) reports published as 
 conference proceedings ; or ( 3 ) published in books . two authors independently assessed each 
 study s risk of bias according to the physiotherapy evidence - based database ( pedro ) 
 scale20 . the pedro scale consists of 10 
 quality ratings , each receiving either a yes or no . the ten items examined were random 
 allocation , concealment of allocation , baseline equivalence , blind therapists , blind 
 subjects , blind assessors , intention to treat analysis , adequacy of follow - up , between - group 
 statistical analysis , point estimates variability . the initial database searches retrieved a total of 244 articles , of which 40 records were 
 excluded due to duplication . after reading the titles and abstracts , 15 full articles were 
 retrieved . three of them did not 
 have any outcome measures related to physical function , two were pre - post studies , three 
 were case studies , one was a conference abstract without full text , and the other was not 
 related to our topic . only five articles ( 4 studies ) that met all the eligibility criteria 
 were included in this review ( table 1table 1.characteristics of included studies in this reviewstudysample size for analysisduration of diabetes ( yrs)age of participants ( yrs ) ( mean  sd)interventionwbv frequency ( hz)wbv amplitude ( mm)treatment duration and session of wbvoutcome measure related to physical functiontime pointresultsbaum k et al.2007 e1/e2/e3=13/13/14uncleare1/e2/e3=63.3  5.9//62.9  7.3/62.2  4.0e1 : stretching;e2 : strength;e3 : wbv+e(eight 
 exercises)30/19 w35/1012 w230 s / set1 set /session ( 16 w)2 set / session 
 ( 79 w)3 sets / session ( 1012 w)3 sessions / w for 12 wmaximal torque of quadriceps ; endurance 
 capacitybaseline12 wwbve improved neither strength ( measured by maximal torque of 
 quadriceps ) nor endurance ( measured by incremental cycle ergometry ) significantly 
 in comparison with the other groups.lee k et al.2013 e1/e2/c=19/18/18e1/e2/c=13.24 4.32/12.29  4.98/11.27  5.78e1/e2/c=76.31  4.78/74.05  5.42/75.77  
 5.69e1 : wbv+bee2 : bec : no any physical 
 training15 ( 1 w)20 ( 23 w)25 ( 45 w)30 ( 6 w)133 * 3  min / session(with 1-min intervals)3 
 sessions / w for 6 wpostural swaybbstugftstsolsfrtbaseline 6wwbv with balance exercise improved balance , muscle strength of 
 elderly patients with diabetic neuropathy compared to be and control.del pozo - cruz j et al.2013 e / c=19/20e / c=10.11  7.29/8.37  8.00e / c=71.60  8.54/66.80  10.83e : wbv+exercise(eight exercise)c : standard 
 care12 ( 14 w)14 ( 58 w)16 ( 912 w)430 s / session3 sessions / w ( 1d between each 
 session ) for 12 wwbb systemtugbaseline12 wsignificant improvements in balance with eyes closed in wbv group . wbv improved the balance of 
 participants with t2dmdel pozo - cruz b et al.2014 e / c=19/20e / c=10.11  7.29/8.37  8.00e / c=71.60  8.54/66.80  10.83e : wbv+exercise(eight exercise)c : standard 
 care12 ( 14 w)14 ( 58 w)16 ( 912 w)430 s / session ( 14 w)45 s / session ( 58 w)60 
 s / session ( 912 w)(with 30 s rest)3 sessions / w ( 1d between each session ) for 12 
 wtug6-mwt30 s sstbaseline12 wwbve exhibited significantly greater improvements on 6-mwtand 
 30s - sst , but no in tug . wbv improved the balance of in participants with t2dmkordi yoosefinejad a et al.2015 e / c=10/10e / c=11  1.6/12  2.0e / c=57  1.8/57  1.5e : wbvc : no any physical training30230  s / session ( 12 w)45  s /session ( 34 w ) 
 1  min / session ( 56 w)2 sessions / w for 6 wtugtustbalance evaluation isometric 
 strengthbaseline6 wwbv enhanced muscle strength and balance of patients with diabetes 
 type 2-induced peripheral neuropathy.wbv : whole body vibration ; wbve : whole body vibration exercise ; ols : one leg stance ; 
 bbs : berg balance scale ; frt : functional reach test ; ftsts : five times sit - to - stand ; 
 wbb : wii balance board ; tug : time up and go test ; 6mwt : six minute walking test ; 
 30s - sts : the 30-s sit - to - stand , fig . 1.search strategy and flow chart for this meta - analysisrct : randomized controlled trial ) . the assessment of the methodological quality is provided in table 2table 2.assessment of the methodology using the pedro scale*criterionbaum k et al.2007lee k et al.2013del pozo - cruz j et al.2013del pozo - cruz b et al.2014kordi yoosefinejad a et al.2015eligibility criterianoyesyesyesyesrandom allocation11111concealed allocation00001baseline comparability11111blind subjects00000blind therapists00000blind assessors01010adequate follow - up01000intention - to - treat analysis00000between group comparisons11111point estimates and variability11111total scores46455*the pedro scores were taken from the pedro website . only one study16 was 
 considered to be a good quality trial ( pedro 67 ) , and the rest were considered to be fair 
 ( pedro 45 ) . wbv : whole body vibration ; wbve : whole body vibration exercise ; ols : one leg stance ; 
 bbs : berg balance scale ; frt : functional reach test ; ftsts : five times sit - to - stand ; 
 wbb : wii balance board ; tug : time up and go test ; 6mwt : six minute walking test ; 
 30s - sts : the 30-s sit - to - stand search strategy and flow chart for this meta - analysis rct : randomized controlled trial * the pedro scores were taken from the pedro website four articles ( three studies)16,17,18,19 assessed balance and mobility using to the 
 timed up and go test ( tug ) . their results showed that the wbv groups demonstrated a 
 significant treatment effect when compared to the control groups . this was regardless of the 
 treatment duration , parameters of wbv , and characteristics of the participants ( wmd , 0.79 ; 
 95% ci , 1.16 to 0.43 ; p<0.0001 , p for heterogeneity<0.00001 ) , with strong evidence 
 for statistical heterogeneity ( i=93% ) ( fig . 
 2fig . ( b ) the aggregated results of tug 
 of two studies : six - week intervention ) . subgroup analysis was done for further analysis meta - analysis of the tug results 
 revealed a significant improvement in favor of six - week wbv for patients with diabetic 
 neuropathy . ( wmd=1.41 , 95%ci=1.84 to 0.98 , p<0.00001 , p for heterogeneity=0.29 , 
 i=12% ) . ( b ) the aggregated results of tug 
 of two studies : six - week intervention this review assessed the effect of wbv on the functional performance of people with t2 dm . although a majority of these studies reported a favorable effect following wbv therapy , some 
 inconsistencies were found in this review . five articles ( four studies ) explored the different aspects of the application of wbv 
 therapy for people with t2 dm . baum k et al.15 compared whole body vibration with exercise ( wbve ) therapy with 
 other kinds of exercise training ( wbv plus exercise vs. exercise ) ; del 
 pozo - cruz j et al . and del pozo - cruz b et al.17 , 
 18 focused on the effect of wbve 
 ( wbv plus exercise vs no physical training ) ; and lee k et al.16 analyzed both of these . the main outcome 
 measures related to physical function were muscle strength , balance , and mobility . three studies assessed the muscle strength using different outcome measures16 , 18 , 19 . using the five times sit - to - stand ( ftsts ) 
 test , lee k et al.16 reported a positive 
 influence on the lower limb strength of patients with diabetic neuropathy who underwent 
 six - weeks of wbv with a balanced exercise program compared to a control group . del pozo - cruz 
 b et al.18 also reported a significant 
 improvement in the 30s sit - to - stand ( 30s - sts ) test in favor of wbv . kordi yoosefinejad a et 
 al.19 reported that the isometric 
 strengths of both the tibialis anterior and quadriceps , which were measured using a 
 back - leg - chest dynamometer , improved after a six - week wbv intervention compared to a control 
 group . muscle strength should be the primary outcome assessed , and muscle strength 
 improvement is the most likely outcome to be influenced by vibration - induced muscular 
 reflex11 . all the results indicate that 
 wbv with or without exercise training has positive effects on the lower extremity muscle 
 strength of people with t2 dm . the improvement of muscle strength may contribute to the enhancement of balance and 
 mobility , but some inconsistencies were still found in this respect . various balance assessments were mentioned in the included studies , including a wii balance 
 board17 , the berg balance scale ( bbs ) , 
 the functional reach test ( frt)16 , and 
 the one leg stance ( ols)/unilateral stance test ( ust)16 , 19 . most studies reported a 
 positive results in the different balance assessments in favor of wbv , except the study by 
 kordi yoosefinejad a et al.19 , which 
 reported that there was no significant difference between the wbv group and the control 
 group according to the ust . del pozo - cruz j et al.17 reported that wbv therapy improved balance performance when the 
 participants eyes closed , which meant that wbv may have stimulated proprioceptive 
 responses , and helped the subjects to acquire a better balance performance21 , 22 . the tug can assess a person s mobility , and it requires both static 
 and dynamic balance23 . lee k et al.16 and koedi yoosefinejad a et al.19 reported a significant improvement in the 
 tug time after wbv therapy , but del pozo - cruz b et al.18 reported an inconsistent result . the meta - analysis of the present 
 study found that the pooled result showed a significant improvement in favor of a six - week 
 wbv for patients with diabetic neuropathy . a possible explanation for this may be that the 
 participants in the studies by lee et al.16 and koedi yoosefinejad a et al.19 all suffered peripheral neuropathy , which may be the major reason 
 behind the deterioration in mobility and dynamic balance , and hence , the changes were more 
 obvious . in addition , the optimal outcome measure of choice for people with t2 dm , with or 
 without neuropathy , is not well studied , and the sensitivity and reliability of the tug test 
 of people with t2 dm without neuropathy may have some bias . besides the problem with balance that people with t2 dm have , issures concerning falls 
 caused by limited balance deserve more attention . in the studies reviewed , only lee et 
 al.16 discussed the possible effects of 
 vibration on the risk of fall , which is strongly related to community mobility and social 
 participation . instead of achieving normal physical function , patients with t2 dm frequently suffer progressive functional 
 degeneration in many aspects25 , and 
 taking this fact into consideration , there is still a lack of evidence to support the 
 long - term effects of wbv therapy on the functional capacity of patients with t2 dm . 
 adequately prolonged follow - up studies are required . in addition , numerous studies did not follow the recommendations of the international 
 society of musculoskeletal and neuronal interactions26 . this may have resulted in bias due to that missing information 
 relating to the intervention parameters and treatment plans . it is , therefore , strongly 
 recommended that future authors reporting on wbv therapy comply with these 
 recommendations . first , our 
 meta - analysis is used a only small number of rcts focused on this area , therefore the 
 conclusions should be interpreted with caution . second , the protocol of wbv and the 
 participants varied greatly , so more quantitative analyses could not be performed . third , 
 exclusion of non - english language studies and some missing and unpublished data may have 
 resulted in bias . as a novel , effective , safe , and alternative approach , wbv therapy may be made available in 
 rehabilitation programs for the management of t2 dm . however , variability in the parameters 
 of wbv therapy can be found , including differences in the levels of vibration and the 
 duration of the interventions . moreover , the characteristics of each patient should also be 
 taken into consideration , such as whether they have diabetic neuropathy or not . overall , the 
 evidence for the application of wbv therapy for the physical function of patients with t2 dm 
 is still inconclusive . more trials using a more specific therapy regimen for wbv therapy for 
 people with t2 dm are needed .
[ purpose ] to review and assess the effectiveness of whole body vibration therapy on the 
 physical function of patients with type ii diabetes mellitus . [ subjects and methods ] 
 a 
 computerized database search was performed through pubmed , medline , embase , the cochrane 
 central register of controlled trials , the physiotherapy evidence database , and the 
 reference lists of all relevant articles . 
 the methodological quality was evaluated using 
 the physiotherapy evidence database scale . [ results ] five articles ( four studies ) with a 
 combined study population of 154 patients with type ii diabetes qualified for the 
 inclusion criteria . 
 our review shows that whole body vibration therapy may have a positive 
 impact on the muscle strength and balance of people with type 2 diabetes mellitus , whereas 
 the effect on their mobility is still under discussion . 
 [ conclusion ] there was no 
 sufficient evidence to support the premise that whole body vibration therapy is beneficial 
 for the physical function of people with type ii diabetes . 
 larger and higher - quality 
 trials are needed .