DM: Physical Activity (2007)

Study Design:
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Quality Rating:
Research Purpose:
To examine the 2-year impact of different increments in energy expenditure on several physiological and biochemical outcome and on direct and indirect social costs in a group of type 2 diabetic subjects who were randomized to an exercise counseling intervention.
Inclusion Criteria:
  • diagnosis of type 2 diabetes for at least 2 years
  • age > 40
Exclusion Criteria:
  • illnesses that could seriously reduce life expectancy or cause cardiac, liver, or renal failure
Description of Study Protocol:

Recruitment :  all patients attending the authors' diabetes clinic between October 1999 and January 2000 were recruited.


  • subjects were instructed to exercise at moderate intensity (40-60% of heart rate reserve) between 3 and 6 METS
  • patients kept daily records of type, intensity, and duration of physical activity
  • if subjects varied their weekly amounts of energy expenditure > 10 METS*h-1*week-1 they were transferred into a group with higher energy expenditure
  • at end of study subjects were divided into groups according to average weekly increases in METs

Blinding used (if applicable) none

Intervention (if applicable)

  • 30 minute counseling session with physician to advise physical activity
  • phone call from same physician 1 month later
  • 15 minute counseling sessions every 3 months for a total of 7 sessions
  • patients were treated for diabetes according to international guidelines
  • overweight and obese patients were advised to follow a diet with a 300-kcal deficit including in the calculation the energy expenditure due to voluntary physical activity

Statistical Analysis

  • change from baseline for continuous variables analyzed using paired samples t tests
  • average rate of change for each variable calculated using linear regressions according to the least squares method
  • a post hoc analysis divided the subjects into 6 groups according to METs*hour-1*week-1, with 10-MET increments
    • this analysis was conducted using ANOVA with post hoc analysis (Tukey's test), and proportions were analyzed using the McNemar test.
    • P values were corrected according to the modified Bonferroni procedure proposed by Finner


Data Collection Summary:

Timing of Measurements: taken every 3 months at outpatient follow-up visits

Dependent Variables

Primary endpoint: CHD risk according to Framingham tables

Secondary endpoints:

  • body weight
  • waist circumference
  • BMI
  • resting heart rate
  • blood pressure
  • HbA1C
  • fasting plasma glucose
  • serum total cholesterol, triglycerides, HDL, LDL  
  • cost analysis
    • direct medical costs, averaged on the year 2000 costs of resources in Italy
    • counseling intervention at a rate of $49 per hour
    • social costs, including
      • value of time spent in physical activity
      • cost of shoes and fitness equipment
      • transportation to exercise place
      • cost of memberships to fitness clubs
      • cost of time lost to work or usual activities due to counseling sessions, illness, or injury  

Independent Variables

  • exercise counseling intervention

Control Variables


Description of Actual Data Sample:

Initial N:182; 88 men

Attrition (final N): 179

Age: 62±0.7 years

Ethnicity: not specified

Other relevant demographics:

Anthropometrics:  age, duration of diabetes, male-to-female ratio, and baseline levels of voluntary physical activity did not differ between groups

Location: Italy


Summary of Results:

69% of the subjects met the study goal of changing their energy expenditure by 10 METS per hour per week.

The intervention increased energy expenditure through voluntary activity by 26±2 METS per hour per week (P<0.0001) in the whole group.

Changes in outcomes of type 2 diabetic subjects divided into six groups on the basis of different amounts of energy expenditure.


Group 0 (no increase in METs)




Group 1-10 (weekly increase of 1-10 METS)



Group 11-20





Group 21-30





Group 31-40





Group >40





Between Group Comp arisons  
              P          Post hoc analysis
Energy Expenditure , METS*hr-1*week-1


6.3±0.4   17.0±0.4  27.0±0.5 37.5±0.5  58.3±1.8   0.000 all groups differ

Weight, kg


0.6±0.7  0.1±0.3   -2.2±0.2**



BMI  0.3±0.2 0.3±0.3 0.03±0.1   -0.8±0.1** -1.0±0.1**  -1.2±0.1 **  0.256  

Waist circumference, cm


 1.0±0.9 -0.9±0.4   -3.8±0.3**

-5.5±0.4 **


 0.000  ABC vs. F
FPG, mmol/l 1.6±2.9 -0.02±0.3  -0.39±0.2   -1.2±0.2** -1.6±0.3**  -1.5±0.1 ** 0.000   A vs. F, B vs. DEF, C vs EF
HbA1c, %  0.03±0.01 -0.06±0.09  -0.4±0.1**  -0.9±0.07** -1.1±0.1**  -1.0±0.1 ** 0.001   B vs. EF
Maximum blood pressure, mmHG  -1.8±0.9 -1.5±0.9  -6.4±2.4 *  -5.6±2.7* -6.6±1.0** 

-9.1±0.6 **


Minimum blood pressure, mmHg  -4.6±2.5 -2.4±0.9  -2.9±1.6 *  -4.8±1.8* -5.3±0.7** -7.1±1.0 ** 0.000  A vs EF, B vs. EF
Heart rate bpm  1.1±0.7 0.5±0.9  -0.9±0.4   -3.8±0.3** -5.6±0.4**  -7.0±0.5**  0.000   A vs. EF, B vs. F, C vs. F
Total Cholesterol, mmol/l  -0.1±0.05 -0.1±0.1  -0.3±0.1 *  -0.3±0.1** -0.2±0.1**  -0.3±0.1 **  0.314  
LDL, mmol/l  -0.1±0.1 -0.2±0.1  -0.1±0.1   -0.1±0.1* 0.2±0.1* -0.2±0.1* 0.376   
HDL, mmol/l  0.1±0.1 1.0±0.1  0.1±0.1   0.1±0.1** 0.3±0.1** 0.2±0.1**  0.000  ABC vs. EF
Triglycerides, mmol/l  0.1±0.1 0.1±0.1  -0.5±0.1 **  -0.6±0.1** -0.6±0.1** -0.8±0.1 **  0.000  AB vs. CDEF
10_year CHD risk, %  0.1±0.3 -0.3±0.5  -2.6±0.6 **  -3.7±0.7  -4.8±1.0  -4.3±1.0  0.000  A vs. CDEF

 *statistically significant from baseline at P between 0.04 and 0.0003

**statistically significant from baseline at P <0.0001


Changes in outcomes of all subjects

Outcome Change P value
Energy expenditure, METs*h-1*wk-1 26.0±1.7  <0.01
Weight, kg -1.3±0.2   <0.01
BMI -0.4   <0.01
Waist, cm -2.7   <0.01
FPG, mmol/l -0.8   <0.01
HbA1c, mmol/l -0.6±0.1   <0.01
Systolic blood pressure, mmHg -5.4±0.6   <0.01
Diastolic blood pressure, mmHg -4.6±1.0   <0.01
Heart rate, bpm -2.80.5   <0.01
Total cholesterol, mmol/l -0.2±0.1   <0.01
LDL, mmol/l -0.2±0.1   <0.01
HDL, mmol/l 0.1±0.1   <0.01
triglycerides, mmol/l -0.4±0.1   <0.01
10-year CHD risk -2.7±1.0  <0.05

Other Findings

 Effect of changes in energy expenditure on medical and social costs over two years

Energy Expenditure Group Change in medical and social costs per person P value
Group 0 (no change in energy expenditure) Increase of $828 <0.01
Group 1-10 no change  
Group 11-20 decrease of $386 <0.0001
Group 21-30 decrease of $1452 <0.0001
Group 31-40 decrease of $2000 <0.0001
Group >40 decrease of $2000 <0.0001
Entire Group decrease of $855 <0.0001

In 2 years, a daily 3-mile walk is estimated to reduce drug costs by $550, other medical costs by $700, indirect social costs by $1100, total costs by $2000, and to increase direct social costs by $400.

Author Conclusion:

This study demonstrates that physical activity is an effective cost-saving tool in the care of type 2 diabetes.

These results confirm the advice of several scientific societies recommending 30 minutes or more of moderate-intensity physcial activity (>10 METs*h-1*week-1) on most days is valid for type 2 subjects and demonstrates a significant dose-response relationship.

Energy expenditure must be >10 METs*hr-1*week-1 for significant beneficial effects.

Energy expenditure ranging between 11 and 20 METs*hr-1*week-1 significantly reduced HbA1c, total cholesterol, triglycerides, and blood pressure and reduced 10-year CHD risk by 2.6%.

Energy expenditure >20 METs*hr-1*week-1 is needed to decrease body weight, BMI, Waist circumference, heart rate, and LDL cholesterol and to augment HDL.  This amount will reduce 10-year CHD risk by 4-5%.

Funding Source:
Reviewer Comments:
Recruitment methods unclear.  Randomization to and treatment of the intervention and control groups not well described.
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? No
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? No
  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? ???
  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? N/A
  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? ???
  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)? No
  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? No
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