PDM: Prediabetes (2013)


Yates T, Davies M, Gorely T, Bull F, Khunti K. Effectiveness of a pragmatic education program designed to promote walking activity in individuals with impaired glucose tolerance: A randomized controlled trial. Diabetes Care. 2009; 32: 1,404-1,410.

PubMed ID: 19602539
Study Design:
Randomized Controlled Trial
A - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

To investigate whether a pragmatic structured education program with and without pedometer use is effective for promoting physical activity and improving glucose tolerance in those with impaired glucose tolerance.

Inclusion Criteria:

Overweight or obese individuals (BMI 25 or more, or 23 or more for South Asians) with screening-detected impaired glucose tolerance (IGT).

Exclusion Criteria:

Individuals who reported taking steroids.

Description of Study Protocol:


Recruited from ongoing population-based diabetes screening programs in Leicester, IK between September 2006 and March 2007.


  • Randomized controlled trial
  • Randomly assigned, using a block design, to receive either usual care, the PREPARE (Prediabetes Risk Education and Physical Activity Recommendation and Encouragement) program or the PREPARE program without pedometer use and were stratified by age and sex. Random assignment conducted using opaque envelopes and a randomly generated number sequence. 


Randomly assigned to one of three groups:

  • Usual care: Participants sent a brief informational sheet in the mail, detailing the likely causes, consequences, symptoms and timeline associated with IGT and how physical activity can be used to treat or control the condition
  • PREPARE program: Single session group-based education program addressing the causes, complications, timeline and identity of IGT and addressing the effectiveness of exercise as a treatment for IGT, walking self-efficacy beliefs, barriers to walking and self-regulatory strategies. Participants were provided with a pedometer and encouraged to set goals based on their baseline activity level.
  • PREPARE program without pedometer use: Participants did not receive pedometers but encouraged to set time-based goals designed to match the advice given to the pedometer group.

Statistical Analysis

Between-group comparisons of change in measured outcomes at three, six and 12 months using ANCOVA procedures with baseline data included as a covariate. Each intervention group was compared with the control group using simple a priori contrasts.

Data Collection Summary:

Timing of Measurements

Baseline, three, six and 12 months after intervention.

Dependent Variables

  • Oral glucose tolerance test: Fasting and two-hour glucose
  • Lipid levels: Cholesterol, HDL-cholesterol, triglyceride
  • Physical activity: Pedometers (sealed piezoelectric pedometers with a seven-day memory), physical activity questionnaire (IPAQ)
  • Psychological analysis: Perceptions and perceived knowledge of IGT were measured with the validated brief illness perceptions questionnaire. Participants' confidence in their ability to exercise in the face of commonly identified barriers was measured using an 11-point Likert scale.
  • Anthropometric data: Weight, height, waist circumference
  • Blood pressure.

Independent Variables

  • Usual care
  • PREPARE program
  • PREPARE program without pedometer use. 
Description of Actual Data Sample:
  • Initial N: 103 (63% male)
  • Attrition (final N): 83 (four additional individuals completed the 12-month period but their data was not included due to diagnosis of diabetes)
  • Age: 65±8 years of age
  • Ethnicity: 75% white, 24% South Asian, 1% black
  • Anthropometrics: No significant difference in BMI, weight or waist circumference at baseline
  • Location: Leicester, UK.


Summary of Results:

Key Findings


Adjusted Intervention Effect (PREPARE with Pedometer vs. Control)

Adjusted Intervention Effect (PREPARE Without Pedometer vs. Control)

Statistical Significance of Group Difference

Two-hour glucose after three months

-1.46 (-2.36 to -0.56)*

0.05 (-0.85 to 0.94)


Two-hour glucose after 12 months

-1.31 (-2.20 to -0.43)*

0.34 (-0.55 to 1.22) *P=0.004

Fasting glucose (mmol per L) after three months

-0.37 (-0.63 to -0.11)*

-0.07 (-0.32 to 0.18)


Fasting glucose after 12 months -0.32 (-0.59 to -0.03)* -0.13 (-0.41 to 0.14) *P=0.028
Ambulatory activity (steps per day) after 12 months 1,902 (954 to 2,859)* 1,401 (417 to 2,385)**


Other Findings

  • No significant difference in either fasting or two-hour glucose in those given the education program without pedometer use compared with that in the control group at any follow-up time point
  • No difference in measured total cholesterol, HDL cholesterol, triglycerides, body weight, waist circumference or systolic blood pressure in either of the intervention groups compared with that in the control group at any time point
  • Compared with the control group, both intervention groups achieved significant increases in perceived knowledge of IGT, perceived effectiveness of exercise as a treatment for IGT and self-efficacy beliefs at 12 months.
Author Conclusion:

Group-based structured education designed to promote increased walking activity through pedometer use is effective for improving glucose tolerance in those with screening-detected IGT, whereas the same program without pedometer use did not result in improved glucose tolerance.

Funding Source:
Other: Diabetes UK
Reviewer Comments:
  • Some data only presented in the online appendix of article 
  • Authors note the following limitations:
    • Small sample size precluded meaningful sub-group analysis
    • Study was conducted in a single center by a dedicated research team, limiting the generalizability of the findings
    • Study methodology did not allow for determination if the success of the pedometer version of PREPARE was solely or partly due to the reactivity of wearing a pedometer and keeping a daily step count log.
Quality Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) Yes
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
Validity Questions
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
2. Was the selection of study subjects/patients free from bias? Yes
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? Yes
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? Yes
3. Were study groups comparable? Yes
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) Yes
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? Yes
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) Yes
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? N/A
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) N/A
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
4. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? Yes
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? Yes
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
5. Was blinding used to prevent introduction of bias? Yes
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? N/A
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) Yes
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  5.5. In diagnostic study, were test results blinded to patient history and other test results? N/A
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? Yes
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? Yes
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? N/A
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? Yes
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? ???
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? Yes
  6.6. Were extra or unplanned treatments described? N/A
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? Yes
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
7. Were outcomes clearly defined and the measurements valid and reliable? Yes
  7.1. Were primary and secondary endpoints described and relevant to the question? Yes
  7.2. Were nutrition measures appropriate to question and outcomes of concern? Yes
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? Yes
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? Yes
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? ???
  7.7. Were the measurements conducted consistently across groups? Yes
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? Yes
  8.1. Were statistical analyses adequately described and the results reported appropriately? Yes
  8.2. Were correct statistical tests used and assumptions of test not violated? Yes
  8.3. Were statistics reported with levels of significance and/or confidence intervals? Yes
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? N/A
  8.6. Was clinical significance as well as statistical significance reported? Yes
  8.7. If negative findings, was a power calculation reported to address type 2 error? Yes
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes