DM: Physical Activity (2007)

Study Design:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
To evaluate the long-term effectiveness (after 6 and 12 months) of physical activity counseling in promoting and maintaining physical activity in people with Type 2 diabetes, and to evaluate the resultant changes in physiological, biochemical and quality of life variables.
Inclusion Criteria:
Participants had Type 2 diabetes controlled by diet, oral hypoglycemic agents or insulin.  They were in either the contemplation or preparation stage of exercise behavioral change.
Exclusion Criteria:
Concurrent medical conditions preventing exercise were excluded.
Description of Study Protocol:


Identified from out-patient clinics in Scotland.


A total of 223 people with Type 2 diabetes were invited to participate with 70 actually participating. Participants were randomized to the experimental or control group.

Blinding used (if applicable):  not possible

Intervention (if applicable)

  • Physical activity couseling was conducted following previously published guidelines and involved a one-on-one discussion with a trained rsearch assistant lasting about 30 minutes.
  • The stage of behavioral change was confirmed during this interview and stage tailored strategies and techniques were used to encourage physical activity. Since all participants were either in the contemplation or preparation stage the strategies and techniques used were similar for all.
  • After the inital consultation some participants progressed to a higher stage of behavioral change. In these participants the physical consultation at 6 months then focused more on preventing relapse to sedentary behavior and on improving long-term maintenance of physical activity.
  • Follow-up phone calls were given 1 and 3 months after each consultation. A general discussion was conducted on previously set activity goals, experienced benefits, barriers and costs of becoming more active and relapse prevention. In the control group the discussion involved topics unrelated to exercise.

Statistical Analysis

  • Repeated measures (time), two-way (time X group) ANOVA models were used to analyze the effect of the intervention on measured outcomes.
  • Covariate adjustments for effects of sex and BMI were applied where appropriate. 
  • For repeated measures analyses, tests were conducted for homogeneity of covariance using a Mauchly spericity test. If data failed this test (P<0.05), a Greenhouse Geisser modification was used.
  • Anderson-Darling tests were performed to test for normality.
  • Variables with non-normal distributions (7-day physical acitivity recall) were transformed using the square root before analysis.
  • Data analysis was conducted using an intent-to-treat basis and with missing values removed.
  • Categorical data were reported as a proportion and were analyzed using chi square or
  • Fisher's exact test. P < 0.05 was significant.
Data Collection Summary:

Timing of Measurements

  • Baseline assessment of demographics,  medical history, physical activity, physiological and biocemical indices.
  • Follow-up phone calls were given at 1 and 3 months. 
  • Follow-up with a repeat of baseline measurements was given at 6 months along with an exercise consultation. 
  • Follow-up phone calls were given at 7 and 9 months. 
  • Baseline assessments were repeated at 12 months.

Dependent Variables

  • Physical activity: 7-day physical activity recall (including time spent per week sleeping, and time spent in light, moderate, hard, very hard and strengthening and flexibility activities) and accelerometer worn for 7 days 
  • Body mass index (BMI): weight in kilogram/height m2
  • Blood pressure: measured from the left arm in a seated position using an automatic blood pressure monitor
  • Exercise test (screening) using a uniaxial accelerometer
  • HbA1c
  • Total Cholesterol
  • HDL cholesterol
  • LDL cholesterol
  • Triglycerides
  • Fibrinogen
  • t-PA

Independent Variables

  •  Physical activity counseling

Control Variables

Medications for hypoglycemia, hypotensive or cardiovascular therapy were collected at each time point and analyzed using chi square tests to determine any significant differences between groups.

Description of Actual Data Sample:

Initial N: 223, with 70 participants selected; 35 experimental, 35 controls

Attrition (final N): 59; 30 experimental, 29 control

Age: mean age of 57.6±7.9 years.

Ethnicity: Not noted by author.

Other relevant demographics: Mean BMI 34.6±6.8, 35 men and 35 women

Anthropometrics No significant differences between the sampled group and the recruited group in terms of sex, age, and BMI (P>0.05).

Location: Scotland

Summary of Results:


Biochemical Outcome Measures



Treatment Group at 6 months


Control group at 6 months

Statistical Significance of Group Difference

Treatment group at 12 months

Control Group at 12 months


Statistical Significance of Group Difference


 0.26% decrease

 0.15% increase


 __  __  P>0.05

Systolic blood pressure

 7.7 mm Hg decrease

 5.6 mm Hg increase


 __  __  P>0.05
Fibrinogen 0.28 mmol/L decrease 1.43 mmol/L increase P<0.05* __ __ P>0.05
Total Cholesterol __ __ P>0.05 0.33 mmol/L decrease 0.04 mmol/L incease P<0.05*

Other Findings

  • No between group differences were found on any measured variable at baseline. 
  • Significant differences between groups were recorded for physical activity after 6 and 12 months (P<0.01).  The experimental group increased physical activty from baseline to 6 months (P<0.01), with no decrease from 6 to 12 months (P>0.05).
  • In the control group accelerometer counts per week decreased from baseline to 12 months (P=0.03). 
  • There were no significant differences in other measured variables.
Author Conclusion:
Physical activity counseling was effective in promoting and maintaining physical activity in people with Type 2 diabetes. The counseling also improved glycemic control as well as the cardiovascular risk factors (blood pressure, total cholesterol, and fibrinogen concentration) in the subjects.
Funding Source:
Reviewer Comments:
  • There were some missing data for biochemical outcomes due to problems obtainng blood samples.
  • A meta-analysis of studies investigating the effect of exercise on BMI in people with Type 2 diabetes after a 2-year physical activity program showed no significant greater change in BMI when exercise conditions were compared to control conditions. Most of the studies in this meta-analysis had follow-up of 2 to 6 months. The disparity in results from this study could be related to the different interventions or the different durations of follow-up.
  • On the 7-day recall, only a small number of participants took part in hard, very hard and strengthening and flexibility activities.  These were combined with moderate activites and analyzed as total activity.
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? ???
  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? ???
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? ???
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? No
  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? Yes
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? Yes
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  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? Yes
  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)? Yes
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? Yes
  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? N/A
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