research sarah m Dennis terry h Diamond
MBBS, FAMAC, is Conjoint Lecturer, Department of
MSc, PhD, is Senior Research Fellow, Centre for
MBBCh, MRCP, FRACP, is Associate Professor
Community Medicine, University of New South Wales,
Primary Health Care and Equity, School of Public
and a general practitioner, Sydney, New South Wales.
Health and Community Medicine, University of New Endocrinologist, St George Hospital Campus,
improving glycaemic and BP control in type 2 diabetes The effectiveness of tai chi type 2 diabetes has been estimated to affect over 100 Background million people worldwide and its prevalence is expected to
This study assessed the effect of tai chi on glycosylated haemoglobin
increase to 300 million by 2025.1 cardiovascular disease is a
(HbA1c), blood pressure and health status (SF-36) in adults with type
major complication and at least 65% of people with diabetes die from cardiovascular disease.2 Weight reduction and exercise are recognised as treatment strategies to control
A randomised controlled trial of tai chi classes for 6 months versus
blood glucose levels and reduce macrovascular risk factors
wait list control for adults with type 2 diabetes and a baseline HbA1c
thereby preventing complications such as cardiovascular disease.1–4 People with diabetes who exercise regularly have better glycaemia control5–8 and cardiovascular
A total of 53 patients were recruited to the study and randomised to
outcomes than those who do not exercise.8–10
tai chi (28) or control group (25). There were improvements in HbA1c;
6 m walk test, and total cholesterol between baseline and follow
Although moderate to vigorous intensity aerobic exercise and
up but the difference between the two treatment groups was not
resistance training have been shown to improve all aspects of
statistically significant. Health status results showed improvements in
insulin resistance syndrome,11 a large proportion of adults with
three domains for the tai chi group.
type 2 diabetes do not follow recommended physical activity
guidelines.12 Tai chi offers a number of advantages as a form
There was no significant improvement in metabolic control or
of exercise and has been demonstrated to decrease blood
cardiovascular risk at follow up compared to the control group.
pressure (BP) and improve lipid profiles.13 It is considered to be an
Patients in the tai chi group showed improvements in physical and
enjoyable activity combining meditation and gentle movements
involving the entire body and has been shown to have a high level of adherence.14–17 It is readily adaptable to differences in physical functioning making it especially suitable for sedentary, overweight or disabled people and can be practised individually or in groups. The aim of this study was therefore to assess the effectiveness of tai chi versus wait list control on HbA1c and BP in adults with type 2 diabetes. A secondary aim was to explore the effect of tai chi on general health status as measured by the SF-36. The study was approved by human research ethics committees of the University of New South Wales and registered with the Australian Clinical Trails Registry (ACTR number 12606000008527). 884 australian Family Physician Vol. 37, No. 10, October 2008 nicholas Zwar MBBS, MPH, PhD, FRACGP, is Professor of General
Table 1. Baseline characteristics of patients randomised in the tai chi for
Practice, School of Public Health and Community
Medicine, University of New South Wales.
We conducted a randomised controlled trial of tai chi classes
versus wait list control for people with type 2 diabetes. Subjects were recruited through advertisements in local papers, a mailout
to Diabetes Australia members and referrals from general
practitioners. Subjects were eligible if they were aged 30 years or
over, had a diagnosis of type 2 diabetes for at least 6 months, had
a HbA1c of >7% and were able to attend tai chi classes twice per
week for 6 months. Subjects were excluded if they were unable
to walk for 10 minutes unaided or if they already participated in
regular exercise classes three or more times per week. Al subjects
Once eligibility had been confirmed, subjects were randomised
to either tai chi or wait list control using a centralised computer
generated al ocation method. Those randomised to tai chi attended two 1 hour classes per week for 3 months and then once per week for a further 3 months. Those randomised to wait list were
effect of tai chi was to reduce HbA1c by 11% and systolic BP
provided with vouchers for tai chi classes to use at the end of the
by 15 mmHg,19 a sample of 40 subjects in each group would
study and were allowed to continue their usual exercise during the
have 0.9 power to detect a significant difference (p=0.05, two
wait list period. The tai chi program for this study was based on
sided). Paired t-test was used to compare the differences between
‘yang and sun style 20-form’, which has been designed for people
baseline and follow up. All data were analysed using SPSS for
Subjects were assessed at baseline and at completion of the
study by either an exercise physiologist or trained nurse, both blinded to the treatment allocation. The measurements included
There were 272 subjects who replied to the advertisements
fasting blood tests for glucose; HbA1c; Homeostasis Model
and underwent telephone screening. Eighty-nine subjects were
Assessment (HOMA), which is a measure of insulin resistance;
excluded at this stage because their HbA1c was <7%, 51 subjects
total cholesterol and triglycerides; height; weight; BP; resting heart
were unable to attend the classes at the times scheduled because
rate; waist and hip circumference; balance; and a 6 m walking test.
of work or they were already taking part in regular exercise classes,
Patients also completed the SF-36 questionnaire.
65 were excluded for other reasons such as pending HbA1c results
The primary outcome measures were a reduction in HbA1c
or not returning cal s. A total of 67 patients attended for baseline
and mean systolic BP compared to baseline. Assuming that the
assessment and of these seven were excluded because their HbA1c
Table 2. Results of paired t-test to compare the difference between tai chi and control
p value Baseline Follow up Baseline Follow up australian Family Physician Vol. 37, No. 10, October 2008 885 research improving glycaemic and BP control in type 2 diabetes – the effectiveness of tai chi
Table 3. Summary of SF-36 item health survey (V. 1.0) mean scale scores for control and tai chi group at baseline and follow up
control (n=22) tai chi (n=24) mean score (sD) mean score (sD)
† = p=0.04, ‡ = p=0.024, * = p=0.044
was <7.0% and a further seven because they refused to have blood
Both the tai chi and control groups demonstrated reductions
tests. A total of 53 patients were randomised to the study. There
in HbA1c, diastolic BP, cholesterol and triglycerides between
were 10 patients who withdrew from the study because of illness
baseline and fol ow up but the difference between the two groups
(5) or time commitments (2). Three patients withdrew toward
was not significant. Several reasons may explain why this might
the end of the study but returned for final blood tests and were
have occurred. The number of patients recruited to the study was
included in the analysis. The baseline characteristics of the 53
smaller than the required sample size and a larger study is needed
patients randomised to the study are described in Table 1.
to exclude a type 2 error. Some of the subjects were excluded
There was a reduction in HbA1c in both groups between
because they were already participating in exercise programs
baseline and follow up but this was not statistically different
or had an HbA1c <7%. The enrolled subjects were not stratified
between those randomised to tai chi or to control. There was a
according to their baseline exercise level at the randomisation
statistical y significant difference between baseline and fol ow up
process. The intensity and duration of the tai chi may not have
for total cholesterol for the tai chi group (p=0.03) but the difference
been optimal to show a demonstrable change. The expected effect
between the two groups was not significant (p=0.79) (Table 2).
of tai chi to reduce HbA1c by 11% and systolic BP by 15 mmHg may
There was a significant improvement in three of the subscales of
the SF-36, role due to physical function (p=0.04), social function
There are data to indicate that exercise of at least moderate
(p=0.024), and general health (p=0.044) with tai chi from baseline
intensity (>20 metabolic equivalent levels [MET] per hour per
to fol ow up but again the difference between the two groups was
week, which is a measure of energy expenditure during exercise)
is necessary to improve cardiovascular outcomes.20 There is also evidence that it is difficult to engage people with chronic diseases
such as diabetes in such intense exercise programs.21 Tai chi is
This is the first community based randomised controlled trial to
a gentler form of exercise and the intensity or duration of the
assess the effectiveness of tai chi for type 2 diabetes compared to
exercise may not have been enough to demonstrate significant
wait list control. There was no statistically significant improvement
change. A recent study by Yeh et al22 reported a significant
in metabolic control or cardiovascular risk after the 6 month period
decrease in HbA1c between pre- and post-exercise measurements
in the tai chi compared to the wait list control group. However, an
but there was no control comparison group. In another study, Orr
improvement was observed in physical and social functioning in
et al23 reported a slight but not significant decrease in HbA1c
the tai chi group from baseline to follow up.
following tai chi. These studies differed from this study with
886 australian Family Physician Vol. 37, No. 10, October 2008 improving glycaemic and BP control in type 2 diabetes – the effectiveness of tai chi research
respect to their duration and number of hours of tai chi per week.
with chronic conditions. Arch Intern Med 2004;164:493–501.
14. A-Forge R. Mind-body fitness: encouraging prospects for primary and second-
In both our study and the Orr study, tai chi classes were scheduled
ary prevention. J Cardiovasc Nurs 1997;11:53–65.
twice a week but three times a week for only 12 weeks in the Yeh
15. Channer K, Barrow D, Barrow R, Osborne M, Ives G. Changes in haemodynamic
study and there was no control group.
parameters following Tai Chi Chuan and aerobic exercise in patients recovering from acute myocardial infarction. Postgrad Med J 1996;72:349–51.
Despite the inconclusive findings of our study, we believe that
16. Kutner N, Barnhart H, Wolf S, McNeely E, Xu T. Self-report benefits of Tai Chi
tai chi, with its relatively low cost, easy accessibility and high
practice by older adults. J Gerontol B Psychol Sci Soc Sci 1997;52:242–6.
adherence rate may still be a useful adjunct for the treatment of
17. Lan C, Chen S, Lai J, Wong M. The effect of Tai Chi on cardiorespiratory func-
type 2 diabetes. The improvements observed in the subscales of
tion in patients with coronary artery bypass surgery. Med Sci Sports Exerc 1999;31:634–8.
the SF-36 indicate that tai chi may have wider health benefits
18. Lam P. Tai Chi for diabetes. 2004 Available at www.taichifordiabetes.com/
for people with type 2 diabetes and are consistent with previous
program.htm. [Accessed 20 September 2007].
reports of the benefits of tai chi in people with chronic disease.13
19. Tsai J, Wang W, Chan P, et al. The beneficial effects of Tai Chi Chuan on blood
pressure and lipid profile and anxiety status in a randomized controlled trial. J
Tai chi as provided in this study may be a useful introduction to
Altern Complement Med 2003;9:747–54.
greater physical activity. However, longer duration or increased
20. Di Loreto C, Fanelli C, Lucidi P, et al. Long-term impact of different amounts of
number of tai chi sessions per week may be required to demonstrate
physical activity on type 2 diabetes. Diabetes Care 2005;28:1295–302.
21. Diabetes Prevention Program Research G. Reduction in the incidence of type 2
significant reductions in metabolic or cardiovascular parameters.
diabetes with lifestyle intervention or metformin. N Engl J Med 2002;346:393–403.
Conflict of interest: none declared.
22. Yeh S, Chuang H, Lin L, Hsiao C, Wang P, Yang K. Tai chi chuan exercise
decreases A1c levels along with increase of regulatory t-cells and decrease of cytotoxic t-cell population in type 2 diabetic patients. Diabetes Care
The authors gratefully acknowledge the RACGP Research Foundation, Pfizer
23. Orr R, Tsang T, Lam P, Comino E, Singh MF. Mobility impairment in type 2 diabe-
and the Australian Association of Academic General Practice (AAAGP) for
tes: Association with muscle power and effect of Tai Chi intervention. Diabetes
the Cardiovascular Research Grant in General Practice that supported this
project; Symbion Laboratory for providing the blood tests free of charge; the St George Division of General Practice for administration of the funds; Diabetes Australia for advice and assistance for recruitment; PHReNet for providing additional funding; GPs for their support; Tracey Tsang and Angela Blair for doing the assessment, Lillias Nairn for preparing study documentation and ethics applications; tai chi instructors Pat Webber and Cheryl Lee Player; and the diabetes subjects. references
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australian Family Physician Vol. 37, No. 10, October 2008 887
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