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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 Discussion
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 Discussion
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 acknowledgments
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.
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