DM: Weight Management (2007)

Study Design:
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Quality Rating:
Research Purpose:

To determine if modest weight loss (>6.8kg) has a long-term benefit for type II diabetes patients.

Inclusion Criteria:

1. >120% of ideal body weight

2. Diagnosis of type 2 diabetes mellitus using the National Diabetes Data Group for type 2 diabetes.

Exclusion Criteria:
Not meeting one of the inclusion criteria standards
Description of Study Protocol:

Recruitment:  Methods not specified

Design:  Nonrandomized Clinical Trial

Blinding Used (if applicable):  Not applicable

Intervention (if applicable):

Behavioral weight control program for 1 year.

Statistical Analysis:

Analyses of covariance were used to compare the changes from pretreatment to one-year follow-up for patients in the five weight loss categories as well as lipid and blood pressure measurements.  Log transformations were used to normalize the distribution of insulin and triglycerides. 

Data Collection Summary:

Timing of Measurements:

At pretreatment and one-year follow-up.

Dependent Variables:

  • HbA1C
  • weight
  • blood pressure
  • cholesterol and triglyceride levels
  • fasting plasma blood glucose

Independent Variables:

  • 114 subjects with type II diabetes were treated in a weight control program and then were followed for one year.

    1. Subjects were treated in groups weekly for 10-16 wk, monthly for the next 6 months, and then at 9 and 12 months.

    2. Subjects were given individualized energy goals designed to decrease weight by 1 kg/wk using either an exchange system or calorie counting diet.

    3. Emphasis of the diet was to decrease fat and simple carbohydrates and to increase complex carbohydrates and fiber.

    4. Subjects were encouraged to increase physical activity with a final goal of walking 3.2 km/d, 5 days/wk.

    5. Behavior modification techniques used were to modify cues in the environment by buying lower energy foods, eating in 1 designated place, and slowing the act of eating.

    Reinforcers used were praise for positive changes, and a deposit of $85 at the start of the study with refunds for weight lost.

Description of Actual Data Sample:

Initial N:125 subjects

Attrition: 114 subjects, 33 men and 81 women

Age: Mean age: 53.5±7.4 yr

Ethnicity:  Not mentioned

Other Relevant Demographics:

  • Mean duration of diabetes diagnosis: 6.5 yr


  • Mean weight: 97.5 kg, 159% ideal body weight

Location:  Pennsylvania




Summary of Results:

Baseline medication use: (number of subjects)

Treatment Number of Subjects
Insulin 21
Oral hypoglycemics 68
Diet only 23
Insulin + oral hypoglycemics 2


  • Weight loss was significantly correlated with improvements in HbA1c values post treatment (r=0.55) and 1 year (r=0.051). Patients who lost more than 6.9 kg or had more than a 5% decrease in body weight, had nonsignificant changes and those gaining weight had significant worsening.
  • Those who lost >10% of body weight over 1 year (n=15) had a significant decrease in HbA1c from 9.7±1.4% to 8.1±0.9% (P<0.001).
  • Those who lost >13.6 kg over the year (n=6) had a significant decrease in HbA1c from 9.7% to 7.1% (P<0.001).
  • Medication use: Those who were on insulin (n=6) and lost >13.6 kg had a significant decrease in insulin use from 151 µU/mL to 21 µU/mL (P<0.001).
Author Conclusion:

These data suggest that modest weight losses may help improve glycemic control in patients with type 2 diabetes mellitus. Although an ideal goal would be sufficient weight loss to normalize HbA1c, with our present weight loss techniques, we did not accomplish this goal for the majority of the patients.

Further research is needed to determine whether decrease in HbA1c levels of 1% to 2% affect the patient’s ultimate prognosis and to develop techniques that produce larger weight losses in diabetic patients.

Funding Source:
Government: National Institute Arthritis Metabolism & Digestive Diseases
Reviewer Comments:

Not all details of the study protocol were included in this manuscript; 3 other articles from this study had been published.

The mean changes in HbA1c did not meet the goals now used in those with type 2 diabetes mellitus. The subjects in this study weighed ~200 lbs, were 159% of ideal body weight and were obese (BMI’s were not given).
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? ???
  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? N/A
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) N/A
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? N/A
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) N/A
  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? No
  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? N/A
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? ???
  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? Yes
  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)? 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? 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