The effectiveness of physical activity in preventing type 2

Journal of Diabetology, June 2012; 2:1
http://www.journalofdiabetology.org/
Review Article:
The effectiveness of physical activity in preventing type 2
diabetes in
high
risk individuals using well -structured
interventions: a systematic review
A.M . M alk aw i
Abstract:
The aim of this systematic review was to evaluate the effectiveness of well-structured interventions
which promote physical activity in high risk individuals with type 2 diabetes. Using ISI web of
knowledge and PubMed data bases in addition to snowballing, a total of 19 articles met the inclusion
and exclusion criteria. Five articles were related to diabetes prevention interventions in USA. Four
articles were related to diabetes prevention interventions in the UK. Five were related to diabetes
prevention interventions in Finland. Five interventions were identified in Netherlands, India, China,
Brazil and Australia. The review found strong evidence regarding the effectiveness of well-structured
physical activity interventions in reducing the incidence of type 2 diabetes. Moreover, well-structured
interventions were also found to be effective in restoring glucose measures including fasting plasma
glucose and 2h plasma glucose. However, there was weak evidence regarding the effectiveness
of well-structured interventions in increasing the level of physical activity. The review suggests using
well-structured lifestyle interventions which include both physical activity and dietary advice. More
research regarding the effectiveness of single physical activity interventions in preventing type 2
diabetes is recommended.
Key words: Physical activity, Exercise, Type 2 diabetes, Prevention
*Corresponding author:
(Current Details)
Ahmad Mohammad Malkawi
Schools of Health and Human Sciences,
University of Essex, Wivenhoe Park, Colchester,
United Kingdom.
E-mail: [email protected]
Introduction:
Diabetes Mellitus is a growing public health
problem worldwide and is considered as one of
the main threats to human health in the 21st
century [1]. The global prevalence of diabetes
in adults aged 20 years or above was
estimated as 171 million in the year 2000. This
figure is expected to double by the year 2030
[2]. Type 2 diabetes mellitus (non-insulin
dependent diabetes mellitus) is the most
common type of diabetes and accounts for 9095% of overall diabetes cases [3].
Pre-diabetic conditions including impaired
fasting
glucose
and
impaired
glucose
tolerance [4,5], being overweight or obese
(Body mass index ≥ 25 kg/m2) [6], family history
(Pag e n u m b er n o t f o r cit at io n p u rp o ses)
Page 1
of diabetes [7], gestational diabetes [8] and
negative lifestyle habits such as lack of exercise
and smoking are considered the main risk
factors for type 2 diabetes [9]. Once diabetes is
diagnosed, it is expensive to treat as a result of
medication costs, regular clinic visits, lab
testing, glucose monitoring and treatment of
complications [10]. Type 2 diabetes is
associated with many complications such as
cardiovascular diseases, renal diseases [11],
advanced skin, muscle, bone infections [12],
impaired quality of life [13] and psychological
effects such as depression or anxiety.
Type 2 diabetes is caused by both genetic and
life style factors. However, the predisposition of
the genetic factor requires the presence of
environmental and life style factors. Moreover,
most of the dramatic increase in type 2
diabetes occurred within populations that
witnessed rapid and major life style changes
[14]. Physical activity can be helpful in the
primary and secondary prevention of diabetes
[15]. There is robust evidence regarding the
protective effect of physical activity in the
development of type 2 diabetes. Studies
Journal of Diabetology, June 2012; 2:1
conducted by Manson et al., (1992), FultonKehoe et al., (2001) and Engberg et al., (2009)
observed that people with a high level of
physical activity were less likely to develop type
2 diabetes in the future [16,17,18].
There is good evidence that physical activity
has many other desirable effects including
better health related quality of life in addition
to the primary and secondary prevention of
many chronic diseases such as cardiovascular
disease, diabetes and cancer [19,20]. However,
few randomized control trials (RCTs) were
conducted regarding the effect of physical
activity in reducing morbidity and mortality [21].
Brisk walk (for at least 150 minutes per week or
30 minutes per day) [22,23], progressive
resistance training such as weight lifting [24]
and yoga exercises [25] have potential benefits
in terms of prevention of type 2 diabetes.
It is already known that physical activity can
prevent diabetes, but it is not known how much
these interventions are successful in prevention
of type 2 diabetes.
The aim of this review was to evaluate the
effectiveness of well-structured interventions
which promote physical activity in prevent type
2 diabetes in high risk individuals.
Methodology
The rationale for this systematic review
One relevant systematic review identified by
Yates et al., assessed the independent effect of
exercise on diabetes risk for people who have
impaired glucose tolerance [26]. Review by
Yates et al., was excellent in terms of its results
synthesis. For instance, the review differentiated
between the interventions which investigated
the effect of exercise alone and those who
used both diet and exercise. However, Yates et
al., included only eight studies in the final
results. He excluded simple intervention studies
which included only a brief written or verbal
physical activity advice [26]. Also, he only
included studies which recruited people with
pre-diabetes (IGT and/or IFG). The current
review can be more comprehensive as it
includes more number of studies (see the results
section). It clearly defines well-structured
interventions and includes all types of high risk
individuals such as obese people, those who
have IGT and/or IFG and people with family
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history of diabetes. Moreover, this review is
updated and includes many studies from 2006
till 2011 (the date when Yates et al., limited his
findings) [26].
Search Strategy
An electronic search was undertaken through
PubMed and ISI web of knowledge database.
The search terms used were “Prevent* diabetes
2” and “promote* physical activity”. The same
research term combination was used for
PubMed and ISI web of knowledge database.
Inclusion and exclusion criteria
Time and language
The search was restricted to English language
with primary source articles published until the
1st of June 2011.
Participants
The review included studies which recruited
people who were at higher risk of developing
type 2 diabetes in the future (as discussed in
the introduction). Studies which recruited
people who already had diabetes were
excluded as the review was concerned about
the primary prevention of type 2 diabetes. In
addition,
participants
were
not
under
medications which alter blood glucose
tolerance or had certain medical conditions
such as cardiovascular diseases which
prevented them from taking part in the
intervention. There was no restriction regarding
the sample size.
Interventions
This review included interventions which
promote physical activity either separately or
as part of a lifestyle or dietary intervention. Any
intervention which was based on medications
only to prevent diabetes such as metformin
and acarbose was excluded. The intervention
should have aimed at preventing type 2
diabetes. Only well-structured interventions
which promoted exercise or physical activity
were included. Glanz et al., argued that
sustained behavioral change could be
achieved by using more tools, strategies and
better understanding of psychological theories
[27]. Brief advice was unlikely to achieve the
desired behavioral change. An intervention
was considered well-structured if it contained
at least two of the following criteria:
Journal of Diabetology, June 2012; 2:1

Curriculum
based
(interventions delivered
certain syllabus).
interventions
according to

Interventions which contained individual
(face to face) sessions.

Interventions
which
used
additional
supportive materials or equipment including
advice leaflets and pedometer.

Theory based interventions or interventions
which used a counseling approach for
changing behaviors (this should be clearly
stated by the author).

Interventions which included teaching
behavior change strategies such as goal
setting, action planning and self-monitoring.

Interventions
which
included
clearly
defined
exercise
recommendations
including exercise type, frequency and
duration (such as 30 minutes brisk walk per
day) or detailed specific supervised
exercise sessions.

Interventions which were developed or
delivered by experts or trained facilitator.
Outcome measures
The study should have assessed the change of
at least one of the following measures as a
result of the intervention; glucose measure, the
level of physical activity and the incidence of
diabetes.
Study design
The review included quantitative studies
including randomized control trials, cohort,
longitudinal pretest and posttest and pilot
studies. The control group should have
received placebo or mini intervention (general
lifestyle advice). There was no restriction
regarding the follow up period of participants.
The process of articles refining
Using ISI web of knowledge data base with the
previously mentioned search terms, 110 articles
were initially identified. This number was
identified when the search was refined to
academic journals, English language and
public, environmental and occupational health
as
subject
areas.
Regarding
PubMed
database, 418 articles were initially identified.
After reading the paper’s titles and abstracts
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and application of inclusion and exclusion
criteria, 19 articles were initially selected from ISI
web of knowledge and 38 articles from Pub
Med. A total of 55 articles were potentially
selected from ISI web of knowledge and
PubMed database. Eight articles were selected
by snowballing from the 55 potential articles.
Twelve articles were selected from the
potential 55 articles and a total of 19 articles
met the inclusion criteria (see appendix 1).
Results
As mentioned previously, 19 articles were finally
selected. Five articles were related to diabetes
prevention programs in USA [23,28,29,30,31].
Four articles were identified related to
interventions in the UK [32,33,34,35]. Five papers
were related to interventions conducted in
Finland [22,36,37,39,40]. One paper each
evaluated interventions in: China [41], Brazil
[42], India [43], Netherland [44] and Australia
[38].
Brief description of the study design and
outcome measurement
To achieve the aim of this systematic review,
the result section focused on two parameters
regarding glucose measures including fasting
plasma glucose and 2-hour plasma glucose.
Moreover, the incidence or cumulative
incidence of diabetes was mentioned if it was
measured by the selected studies. In addition,
three parameters were used to assess the
change in physical activity level among
participants including self-reported physical
activity, aerobic fitness (VO2 max) and the
ambulatory activity. Finally, syntheses of the
results were done using glucose and physical
activity parameters according to the follow up
period (3 months to 10 years).
The effect of well-structured interventions on
reducing glucose measures
Yang et al., (2009) and Thompson et al., (2008)
found no significant improvement in fasting
plasma glucose after three and six months
respectively [28,31]. However, Allen et al.,
(2008) found a significant improvement in
fasting plasma glucose after six months follow
up [29]. The process of recruitment in the three
previously mentioned studies was done through
voice mail messages, flyers posted in hospitals
and advertisements in local newspapers. This
Journal of Diabetology, June 2012; 2:1
facilitated targeting different kinds of people
and advertisements in local newspapers. This
facilitated targeting different kinds of people
and reduced the possibility of selection bias.
However, Yang et al., (2009) et al., and Allen et
al., (2008) recruited small number of
participants [29,31]. Kinmonth et al., (2008) and
Thompson et al., (2008) found no significant
improvement in fasting plasma glucose after
one year follow up [28,32]. Sartorelli et al.,
(2005) and Absetz et al., (2007) found no
significant improvement both in 2-hour glucose
and fasting plasma glucose measures during
the same period [39,42]. Absetz et al., (2007),
Sartorelli et al., (2005) and Kinmonth et al.,
(2008) recruited participants from general
practices
or
health
centers
[32,39,42].
Therefore, these studies were prone to selection
bias. On the other hand, Yates et al., (2009),
Laatikainen et al., (2007), Tuomilehto et al.,
(2001) and Lindström et al., (2003 b) found that
fasting plasma glucose and 2 h plasma glucose
were decreased significantly after one year
follow up [22,34,36,38]. Allen et al., (2008) found
that the mean change of fasting blood glucose
was significantly reduced after 18 months
follow up [29]. The studies which were carried
out by Yates et al., (2009), Lindström et al.,
(2003 b), Tuomilehto et al., (2001) and
Laatikainen et al., (2007) were also prone to
selection bias [22,34,36,38]. For example, Yates
et al., (2009) recruited participants from
diabetes screening program in Leicester [34].
Studies conducted by Yates et al., (2009),
Lindström et al., (2003 b), Tuomilehto et al.,
(2001), Sartorelli et al., (2005) and Kinmonth et
al., (2008) were partly blinded randomized trials
[22,32,34,36,42]. It was difficult to conduct a
double blinded trial because trainers who lead
well-structured physical activity sessions had to
know group allocation. Lindström et al., (2003
b) and Mensink et al., (2003) found a significant
improvement in 2-hour glucose after 2 years
follow up [36,44]. Yates et al., (2011) found
significant improvement in both fasting plasma
glucose and 2 h glucose after 2 years follow up
in the group which received both structured
education and pedometer [35]. Lindström et
al., (2003 a) found no significant improvement
in fasting plasma glucose and 2 hour plasma
glucose after 3 years follow up [37]. Knowler et
al., (2002) found a significant reduction in
fasting plasma glucose after 4 years follow up
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[23]. The US diabetes prevention program
provided a longer term results and found that
the mean of fasting glucose improved after 10
years follow up [30]. However, a long follow up
period had a problem of high number of
participants who dropped out during the study.
In summary, there is good evidence that
effectiveness of well-structured interventions
can improve glucose measures. Most of the
positive results came from the US and Finnish
diabetes prevention programs which have
larger sample size and long follow up period
(see the results table).
The effect of well-structured interventions on
reducing the incidence of type 2 diabetes
All studies which were identified found a
significant reduction in the cumulative
incidence of diabetes including Tuomilehto et
al., (2001), Ramachandran et al., (2006),
Knowler et al., 2002, Pan et al., 1997, Diabetes
Prevention Program Research Group et al.,
2000 and Lindström et al., (2003 b)
[22,23,30,36,41,43]. For example, the US
diabetes prevention program recorded that
the incidence of diabetes was 58% lower in the
intervention than that of the control group after
an average of three years follow up [23]. The
studies which measured the incidence of type
2 diabetes gave better indication regarding
the effectiveness of these programs because
studies may find significant improvement in
fasting plasma glucose or 2 hour plasma
glucose measures among participants, but it
was difficult to determine if there was an actual
reduction in the number of patients with
diabetes.
The effect of well-structured interventions on
increasing the level of physical activity
Thompson et al., (2008), Greaves et al., (2008),
Kinmonth et al., (2008), Sartorelli et al., (2005)
and Allen et al., (2008) found no significant
improvement in self-reported physical activity
after a follow up period that ranged between
six and 18 months [28,29, 32,33,42]. On the other
hand, Laatikainen et al., (2007), Lindstr ِm et al.,
(2003a), Tuomilehto et al., (2001), Yates et al.,
(2009) and Lindstrِm et al., (2003 b) found that
self-reported physical activity significantly
improved after
one
year
follow
up
[22,34,36,37,38]. Kinmonth et al., (2008), Allen
Journal of Diabetology, June 2012; 2:1
et al., (2008) and Thompson et al., (2008) found
no
significant
improvement
in cardio
respiratory fitness (VO2max) after one year and
16 months follow up period [28,29,32]. Yates et
al., (2009) found that the ambulatory activity
improved after one year follow up [34].
Mensink et al., (2003)
found
that
the
aerobic fitness significantly improved after 2
years [44]. Ramachandran et al., (2006) found
significant
improvement
in
self-reported
physical activity after 30 months follow up [43].
Lindstrِm et al., (2003 a), Knowler et al.,
(2002), Laaksonen et al., (2005) and Pan et
al., (1997) found a significant increase in selfreported physical activity after three and four
years follow up [23,37,40,41].
In summary, there is weak evidence regarding
the
effectiveness
of
well-structured
interventions in increasing the level of physical
activity as the majority of studies relied only on
self-reported data in addition to the fact that it
is difficult to measure physical activity in
general.
Can physical activity alone be enough to
prevent type 2 diabetes?
Four studies which were carried out by
Kinmonth et al., (2008), Yates et al., (2009),
Yang et al., (2009) and Yates et al., (2011) were
single
physical
activity
interventions
[31,32,34,35]. Only Yates et al., (2009) and Yates
et al., (2011) who assessed PREPARE program
found effectiveness in restoring glucose
measures [34,35]. Interestingly, the Chinese
diabetes intervention allocated participants
into four groups: control, diet, exercise and diet
+ exercise groups. After an average of six years
follow up, there was no significant difference in
the incidence of diabetes between the three
intervention groups which means that physical
activity intervention has a similar effect to both
diet and physical activity intervention [41].
However, most of the positive results were
recorded from lifestyle interventions which
included both diet and lifestyle counseling.
Therefore, it is difficult to confirm that physical
activity alone is enough to prevent type 2
diabetes and there is still a need for more
research in this area.
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Discussion
The results found a potential effectiveness of
well-structured interventions which include
promoting physical activity especially in terms
of reducing diabetes incidence and improving
glucose measures. The quality and strength of
each paper included in this review can lead to
different results. Moreover, other factors can
play an important role including the nature of
the control group and the accuracy of glucose
tests. Regarding the nature of the control
group, it differed from one study to another.
Most of the trials provided the control group
with a mini intervention for ethical reasons. For
example, the trial which was carried out by
Tuomilehto et al., (2001) to assess the
effectiveness of the Finnish diabetes prevention
program provided the participants of the
control group with only annual oral and written
information based on diet and exercise advices
without individual counseling [22]. Whereas,
Knowler et al., (2002) who assessed the US
program provided participants of the control
group with 20-30 minutes of annual individual
session [23].
Regarding the accuracy of
glucose tolerance tests, some studies such as
Knowler et al., (2002) conducted more than
one glucose test to validate their results, while
others such as Allen et al., (2008) conducted
only one test [29]. Most of the studies which
found positive results regarding the effect of
well-structured interventions were conducted
according to the Finnish, US, Chinese and
Indian diabetes prevention programs in
addition to PREPARE intervention (the UK
program). The most common themes between
all these interventions are that they were
conducted at national level, had clearly
defined physical activity objectives (such as 30
minutes of daily walking) and were more likely
to provide personal counseling sessions. In
addition, most of them were lifestyle programs
(included
both
dietary
and
exercise
interventions). Lifestyle interventions were
considered too expensive as a result of the cost
of delivering the intervention including trained
health care educators, the cost of exercise
equipment and the cost of participant’s time
[45]. On the other hand, lifestyle interventions
have multiple positive health outcomes
including reducing the body mass index,
improving blood pressure, prevention of
Journal of Diabetology, June 2012; 2:1
hypertension and many chronic illnesses [46].
These results can be partly agreed with Rutter
and Quine (2002) who said that good
interventions must be theory driven, tackle an
important health issue and have a clearly
defined process of outcome evaluation [47].
The
IMAGE
toolkit
provides
clear
recommendations regarding effective diabetes
prevention programs. The toolkit recommends
using both diet and physical activity counseling
to prevent diabetes. Moreover, it suggests
clearly defining the targeted group and use
different
counseling
approaches
during
counseling. Counseling can include teaching
participants many important skills such as goal
setting, action plan and problem solving to
identify barriers and give solutions to these
barriers. In addition, counseling can include
raising awareness regarding the benefits of
physical activity. This toolkit suggests using
many supportive materials such as audio visual
equipment, illustrations and nutritional diaries.
Finally, it IMAGE recommends using a structured
evaluation sheet to facilitate evaluating the
intervention [48].
There are a lot of challenges regarding the
implementation of well-structured interventions.
At first, it is important to apply more effective
approaches to identify high risk people rather
than targeting people from GPs or health
centers. Therefore, it is important to use various
ways to recruit participants such as mass
media, health centers and emails [48].
Moreover, a special consideration should be
given
when
applying
well-structured
intervention in countries where there is lack of
adequate infrastructure and sport facilities. To
achieve sustainable results, it is important to
provide sidewalks and bike paths to encourage
walking and cycling and collaborate with nonprofit organizations and policy makers in order
to target the social environment [48,49].
Furthermore, it is important to consider the
context in addition to the cultural and religious
barriers to ensure that the intervention is
acceptable and suitable to the target
population [50].
One of the issues which should be considered
before
implementing
physical
activity
interventions is the assessment and recording of
physical activity during patient follow up.
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Physical activity can be assessed subjectively
using self-reported questionnaire or objectively
(directly measured) using certain equipment’s
such as pedometers [51]. Self-reported
questionnaires are commonly used because
they are cheap and easy to use [52]. However,
both methods have drawbacks and are
subjected to potential bias [53]. Self-reported
questionnaires do not account for less than 10
minutes physical activity and may not be able
to capture all types of physical activity.
Whereas, using certain devices to measure
physical activity may not be worn in activities
such as swimming [51, 53]. Troiano (2012)
recommended using both objective and
subjective measurements to validate our results
and get better measurement and recording of
physical activity [54].
Limitations
This systematic review has many limitations. It
only included English language articles. Many
high quality articles which are written in
German, French and Swedish may not
included and this may affect the final results.
This review included only published articles,
excluding
grey
literature
(unpublished
literature) can make the review prone to
publication bias. Hopewell et al., (2009) found
that trials which show a positive effect are more
likely to be published rather than interventions
which show a negative or no effect at all [55].
Moreover, including only published literature
may ignore hidden evidences which could be
relevant to this review. Factors related to time
restraints in addition to that it is based on a
single novice researcher effort the thing which
makes it not as thorough as an experienced
research team [56]. Most of the interventions
which were included in this review excluded
participants with certain medical conditions
such as cardiovascular diseases for ethical
reasons. This may lead to exclusion of a large
population who are at risk of developing type 2
diabetes.
Conclusion
Type 2 diabetes mellitus is a significant public
health problem. It has significant burden at the
individual and national level. There is strong
evidence that physical activity is effective in
the primary prevention of type 2 diabetes and
Journal of Diabetology, June 2012; 2:1
its associated diseases as well as other chronic
diseases. Although we know that physical
activity can prevent type 2 diabetes, we still
need to know and evaluate the effectiveness
of the interventions which promote physical
activity in the real world. This review found that
there is a good evidence of the effectiveness
of well-structured interventions in reducing
glucose measures and stronger evidence
regarding reduction in the incidence of type 2
diabetes. However, it found weak evidence
regarding the effectiveness of well-structured
interventions in increasing the level of physical
activity because most of the studies rely on selfreported questionnaires. Therefore, it is
recommended for future studies to measure
physical activity subjectively and objectively to
support their findings. Moreover, this review
cannot give any recommendations regarding
the type, duration and intensity of physical
activity which is more effective in prevention of
diabetes. There is need of more research to
answer many questions. For instance, can six
sessions per day (five min per session) achieve
the same benefit as single daily 30 minutes
session? [57]. Can various amounts of moderate
and vigorous intensity of physical activity below
the recommended threshold be combined to
meet the recommended level? [21]. There is
need for more research to confirm if physical
activity alone can be enough to prevent type 2
diabetes. Moreover, it is recommended to
implement lifestyle interventions because most
of the positive results were recorded from them
and they have many other health benefits.
Before implementing a physical activity
intervention anywhere, it is important to ensure
that it has clearly defined objectives and
process
of
evaluation in addition to
implementing
culturally
accepted
interventions. It is important to apply more
effective ways to identify people who are at
high risk of type 2 diabetes rather than relying
on GPs. In addition, it is recommended to
support these interventions with adequate
infrastructure.
Acknowledgements
The author is grateful to Dr. Vale Thurtle who
supervised him in his dissertation and provided
valuable feedbacks for this literature review.
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33. Greaves C, Middlebrooke A, O'Loughlin L,
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Appendix 1: Flow chart showing article search, inclusion criteria and selection process
Search engine: PubMed and ISI web of knowledge
Main Search terms:
“Prevent* diabetes 2” AND “promote* physical activity”
Refining the ISI
research with:
Academic journals,
English language and
public, environmental
and occupational
health as subject areas
418 articles were
initially identified by
Pub Med
110 articles were initially
identified by ISI web of
Knowledge
ledge
According to inclusion and
exclusion criteria and after
reading titles and abstracts
18 articles were
potentially relevant from
ISI web of Knowledge
38 articles were
potentially selected
from Pub Med
55 overall articles were
potentially relevant from
the two databases
8 articles were
identified by
snowballing
(Pag e n u m b er n o t f o r cit at io n p u rp o ses)
19 articles were finally selected
and met all the inclusion criteria
Page 11
Journal of Diabetology, June 2012; 2:1
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Appendix 2: Summary of the results of the final selected studies
Author/date
Aim of study
Type of the study
Main findings/conclusion
Strengths and limitations
Knowler et al., (2002)
To assess the
effectiveness of
intensive lifestyle
intervention (The US
diabetes prevention
program) in prevention
of diabetes
Randomized control
trial
Significantly lower incidence
of diabetes cases and higher
leisure time physical activity in
the intervention group after
an average of 2.8 years follow
up.
Representative sample
There was a significant
reduction in fasting plasma
glucose in the intervention
group during 2.8 years follow
up.
Diabetes Prevention
Program Research
Group et al., (2009)
To assess the
effectiveness of
intensive lifestyle
intervention (The US
diabetes prevention
program) against
general lifestyle
recommendations in
prevention of diabetes
Cohort study
After 10 years follow up, the
incidence rate did not differ
significantly between the
lifestyle intervention and the
control group. However, the
cumulative incidence rate
(overall new diabetes cases
over 10 years) of diabetes
was the least in lifestyle
intervention
The mean of fasting glucose
concentration in the lifestyle
intervention was less than the
control group
(Pag e n u m b er n o t f o r cit at io n p u rp o ses)
Page 12
Good sample size (3234)
Partly blinded study
Unclear process of follow up including the
number of participants who dropped out
Exercises were assessed by self-reported
questionnaire.
This study was designed similar to (Knowler
et al., 2002), but the follow up period was
extended to 10 years.
Possibility of other confounding factors as a
result of long follow up period
Journal of Diabetology, June 2012; 2:1
Allen et al., (2008)
To evaluate lifestyle
intervention which was
conducted to prevent
type 2 diabetes among
American Indian
women with impaired
glucose tolerance
http://www.journalofdiabetology.org/
Randomized control
trial
The mean change of fasting
blood glucose was
significantly reduced among
participants (in comparison to
baseline) after 6, 12 and 18
months follow up.
Small sample size (42)
Less prone to selection bias
Exercise were assessed by self-reported
questionnaire
No significant improvement in
the total leisure time physical
activity during the same
period.
Thompson et al.,
(2008)
Yang et al., (2009)
To evaluate lifestyle
intervention which was
conducted to prevent
type 2 diabetes among
American Indian
women with impaired
glucose tolerance
To evaluate the
feasibility of 3 months
yoga program in
preventing type 2
diabetes for people at
risk
Randomized control
trial (with 18 months
follow up for
American Indian
women)
No significant change in the
mean of fasting blood
glucose among participants
during 6, 12 and 18 months
follow up.
A sample size of 200
Participants were randomized by tow
computer generated lists
Less prone to selection bias
No significant improvement in
the total leisure time physical
activity and aerobic fitness
(VO2) during the same
period.
Randomized control
trial (with 3 months
follow up)
The intervention group
showed improvement in
exercise self-efficacy.
No significant improvement in
fasting glucose level.
Exercise was assessed by self-reported
questionnaire and aerobics fitness (VO2)
Including subjects from different ethnicity
Less prone to selection bias
Small sample size (23)
Unclear process of randomization
The questionnaire which used for assessing
exercise cannot be reliable in terms of
measuring the change exercise practicing
because it asses perceived self-efficacy to
participate in physical activity
(Pag e n u m b er n o t f o r cit at io n p u rp o ses)
Page 13
Journal of Diabetology, June 2012; 2:1
Yates et al., (2009)
To evaluate the
effectiveness of
(PREPARE) program,
which promote walking
activity with or without
pedometer, in
improving impaired
glucose tolerance
http://www.journalofdiabetology.org/
Randomized control
trial
A structured education
program with pedometer use
(PREPARE) is effective in
reducing fasting plasma
glucose and 2 h glucose after
one year follow up.
Small sample size (87)
More men than women participated
Partly blinded study
Short follow up period
Clear process of randomization
Physical activity was measured subjectively
(by questionnaire) and objectively (by
pedometer)
Greaves et al., (2008)
To assess the
effectiveness of
simplified intervention
based on motivational
interviewing, in
changing weight and
physical activity
among people at high
risk of diabetes.
Randomized control
trial
A higher proportion of
participants achieved the
recommended physical
activity (150 minute of
moderate physical activity
per week), but the difference
was not significant, after 6
months follow up
Small sample size (144)
Partly blinded study
Short follow up periods (6 months)
Only included people who speak English
fluently
Exercise were assessed by self-reported
questionnaire
Yates et al., (2011)
To evaluate the
effectiveness of
(PREPARE) program,
which promote walking
activity with or without
pedometer, in
improving impaired
glucose tolerance
(Pag e n u m b er n o t f o r cit at io n p u rp o ses)
Randomized control
trial
Page 14
A structured education
program with pedometer use
(PREPARE) is effective in
reducing fasting glucose
tolerance and 2 h glucose
after 2 years follow up.
No glucose measurement
The study design is similar to that which was
conducted by Yates et al., (2009)
Journal of Diabetology, June 2012; 2:1
Tuomilehto et al.,
(2001)
To assess the effect of
exercise and dietary
life style intervention
(The Finnish diabetes
prevention program) in
preventing type 2
diabetes for people
who are at risk.
http://www.journalofdiabetology.org/
Randomized control
trial
The Finnish diabetes
prevention program showed
significant reduction in fasting
plasma glucose and 2 h
plasma glucose among the
intervention group after one
year follow up.
Sample size of (523)
Clear process of randomization
Partly blinded study
Exercise was assessed only by self-reported
questionnaire
Achieving the exercise goal
(more than 4 hrs weekly) was
significantly higher among the
intervention group after one
year follow up.
The incidence of diabetes
was lower and statistically
significant in the intervention
group than the control group
after 2 years follow up.
Lindström et al., (2003
a)
To assess the effect of
exercise and dietary
life style intervention
(The Finnish diabetes
prevention program) in
preventing type 2
diabetes for people
who are at risk.
(Pag e n u m b er n o t f o r cit at io n p u rp o ses)
Randomized trial
Page 15
The Finnish diabetes
prevention was effective in
reducing fasting plasma
glucose and 2 h plasma
glucose only after one year
(not after 3 years). In addition,
it increased the level of
moderate to vigorous leisure
time physical activity after
one and 3 years.
The same design of Tuomilehto et al.,
(2001)
The study showed results after 3 years follow
up
Journal of Diabetology, June 2012; 2:1
http://www.journalofdiabetology.org/
Lindström et al., (2003
b)
To assess the effect of
exercise and dietary
life style intervention
(The Finnish diabetes
prevention program) in
preventing type 2
diabetes for people
who are at risk.
Randomized control
trial
The Finnish diabetes
prevention was effective in
reducing diabetes risks such
as fasting plasma glucose
and 2 h plasma glucose after
one and two years. In
addition, achieving the
physical activity goal was
significantly higher among the
intervention group after one
year.
The same design of Tuomilehto et al.,
(2001)
Laaksonen et al.,
(2005)
To assess the effect of
exercise and dietary
life style intervention
(The Finnish diabetes
prevention program) in
preventing type 2
diabetes for people
who are at risk.
Randomized control
trial
Only moderate and vigorous
in addition to strenuous
structured physical activity
showed significant difference
among intervention group
after an overall of 4 year
follow up.
The same design of Tuomilehto et al.,
(2001)
To evaluate the
effectiveness GOAL
lifestyle intervention in
prevention of type 2
diabetes
Longitudinal pretest
and posttest study
design
No improvements in fasting
glucose and 2 hr oral glucose
challenge after one year
follow up.
Prone to selection bias
Absetz et al., (2007)
The study provided detailed description of
physical activity after longer period of follow
up
More female (265) than males (87)
participated in the study
Physical activity was assessed by selfreported questionnaire
(Pag e n u m b er n o t f o r cit at io n p u rp o ses)
Page 16
Journal of Diabetology, June 2012; 2:1
Sartorelli et al., (2005)
To evaluate the
effectiveness of low
cost lifestyle
intervention in
prevention of diabetes.
http://www.journalofdiabetology.org/
Randomized control
trial (with one year
follow up)
Only significant improvement
in fasting plasma glucose
after the first 6 months.
No significant improvement in
fasting plasma glucose after
one year in addition to 2 h
plasma glucose after 6
months and one year.
No significant improvement in
achieving the physical
activity goal
Laatikainen et al.,
(2007)
Pan et al., (1997)
To evaluate the
feasibility of life style
intervention which was
conducted in
Australian primary care
in prevention of
diabetes
Longitudinal pretest
and posttest study
design
To evaluate the
effectiveness of diet
and\or exercise
intervention in
reduction of the
incidence of diabetes
among people with
impaired glucose
tolerance.
Randomized control
trial
Page 17
Exercise was assessed by self-reported
questionnaire
Partly blinded study
Unclear process of randomization
Large number of people lost during follow
up
Significant improvements in
fasting glucose and 2 hr oral
glucose challenge after one
year follow up.
Prone to selection bias
Significant improvement in
physical functioning after one
year follow up
After 6 years follow up, the
incidence and cumulative
incidence of diabetes was
significantly lower in the
intervention group, who
received either diet or
exercise or both, in
comparison with the control
group
Physical activity was assessed by selfreported questionnaire
Self-reported physical activity
level was significantly higher
in intervention groups (in
comparison with baseline)
(Pag e n u m b er n o t f o r cit at io n p u rp o ses)
Small sample size (104)
More female (172) than males (65)
participated in the study
Good sample size (577) with long follow up
period (6 years)
Assessed the effect of physical activity
alone in the reduction of diabetes cases
Prone to selection bias
Un clear process of randomization
Journal of Diabetology, June 2012; 2:1
Ramachandran et
al., (2006)
Mensink et al., (2003)
http://www.journalofdiabetology.org/
To assess the
effectiveness of
lifestyle intervention
in reducing diabetes
cases among Asian
Indians with impaired
glucose tolerance.
Randomized control
trial
To assess the effect of
diet and physical
activity intervention
(Dutch program) on
glucose tolerance for
people who are at risk
of developing diabetes
Randomized control
trial
The cumulative incidence of
diabetes was significantly
lower in the intervention
groups
Unclear process of randomization
Blinding was not achieved
The level of physical activity
improved from baseline in
both the lifestyle intervention
group
Page 18
More men (412) than women (110)
participated in the study
Only 2-h glucose was
significantly lower in the
intervention group after 2
years.
Use of exercise test to measure physical
activity
Participants in the intervention
group significantly improved
their aerobic fitness.
Prone to selection bias
Subjects who received both
diet and exercise intervention
significantly improved their
fasting insulin measures (2-h
glucose was improved, but
the improvement was not
significant)
(Pag e n u m b er n o t f o r cit at io n p u rp o ses)
Sample size of (531)
Small sample size (114)
Partly blinded.