PDM: Prediabetes (2013)


Katula JA, Vitolins MZ, Rosenberger EL, Blackwell CS, Morgan TM, Lawlor MS, Goff DC Jr. One-year results of a community-based translation of the Diabetes Prevention Program: Healthy-Living Partnerships to Prevent Diabetes (HELP PD) Project. Diabetes Care. 2011; 34(7): 1,451-1,457.

PubMed ID: 21593290
Study Design:
Randomized Controlled Trial
A - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:

To report the first-year results of a community-based translation of the Diabetes Prevention Program (DPP) lifestyle weight loss (LWL) intervention on fasting glucose, insulin resistance, and adiposity.

Inclusion Criteria:
  • Have evidence of prediabetes on two occasions
  • A confirmatory fasting glucose between 95 and 125mg per dL
  • BMI 25.0kg/m2 or more and 39.9kg/m2 or less
  • Signed informed consent.
Exclusion Criteria:
  • Recent history of an acute cardiovascular disease event
  • Clinical history of type 2 diabetes
  • Uncontrolled hypertension
  • Cancer or other conditions limiting life expectancy
  • Chronic use of medicines known to influence glucose metabolism (i.e., corticosteroids)
  • Major psychiatric or cognitive problems, including depression
  • Participation in a supervised program for weight loss or another research study that would interfere with HELP PD
  • Pregnancy
  • History of substance abuse
  • Unable to perform exercise (The Physical Activity Readiness Questionnaire was administered to identify people with contraindications to exercise, who were required to obtain a medical clearance from their physician).
Description of Study Protocol:


Subjects were primarily recruited through mass mailings to targeted ZIP codes. Interested individuals went through a tiered screening process. They were telephone screened and then invited to a study information session. Eligible individuals were then scheduled for a clinic screening visit and those who remained eligible were scheduled for a randomization visit.


Randomized controlled trial.

Blinding used

No blinding was used for subjects and investigators. However, it was noted that all biochemical measurements were performed in a central laboratory by technicians masked to the intervention assignment.


  • Subjects were randomly assigned to:
    • A group-based translation of the DPP LWL intervention administered through a diabetes education program (DEP) and delivered by community health workers (CHWs)
    • An enhanced usual-care condition
  • CHWs were volunteers with well-controlled type 2 diabetes. The LWL intervention group met weekly for CHW-led group sessions during the first six months, as well as received three personalized consultations with a registered dietitian (during months one, three and six). During months seven to 12, they received two scheduled contacts with the CHW each month, one group session and one telephone contact. The enhanced usual-care group, which served as the control, received two individual sessions with a nutritionist during the first three months involving healthy eating and physical activity education to support weight loss, as well as a monthly newsletter with topics related to healthy lifestyle and information about community resources.

Statistical Analysis

  • With a total sample size of 300 subjects randomly assigned, it was estimated that the trial has 81% power to detect a 3mg per dL difference between groups and 91% power to detect a 3.5mg per dL difference in fasting glucose
  • The randomization procedure involved a permuted block design with varying block size
  • Arithmetic means and SDs are presented for continuous variables. For baseline comparisons between the two groups, T-tests were used for continuous variables and the Fisher exact test was used for categorical variables.
  • General linear models for repeated-measure ANCOVA were used to compare the main effect of the intervention on the six- and 12-month values. For each outcome measure, the baseline value for that outcome was used as a covariate.
  • The test for intervention effect is based on the least square means of the estimated main effect of intervention (estimate of the average of the six- and 12-month means)
  • The intention-to-treat approach was used and included all post-randomized values according to the group to which they were assigned. Secondary analyses were performed, making a reasonable exception to this rule by deleting observations at visits where the subject was taking hypoglycemic medication.
  • Inferences for comparisons were tested at a 5% two-sided level of significance
  • An unstructured variance model was used for intrasubject longitudinal covariance.
Data Collection Summary:

Timing of Measurements

Fasting blood glucose, insulin, and anthropometry were assessed at baseline and randomization and at the six- and 12-month visits.

Dependent Variables

  • Fasting glucose (primary outcome measure)
  • Insulin
  • Insulin resistance: Examined using the homeostasis model assessment of insulin resistance (HOMA-IR) index [HOMA IR=({fasting insulin x fasting glucose}/22.5)]
  • Weight
  • Body mass index (BMI)
  • Waist circumference
  • Percentage weight loss.

Independent Variables

  • A community-based translation of the DPP LWL intervention, which targeted decreased caloric intake (goal of 1,200 to 1,800kcal per day) and increased caloric expenditure through moderate physical activity (goal of 180 minutes or more per week), with the primary objective of a total weight loss of 5% to 7% during the first six months of treatment. 

Control Variables

  • Age
  • Race
  • Educational attainment

(More details in another paper published by the authors.)

Description of Actual Data Sample:
  • Initial N: 301 (128 males, 173 females)
  • Attrition (final N): Information was available regarding the primary outcome, fasting glucose, for 280 (93.4%) participants at month 6 and 273 (90.2%) participants at month 12.
  • Age: 57.9±9.5 years
  • Ethnicity: 74.0% white, 24.7% African American, and 1.3% other
  • Other relevant demographics: 80% reported having an education beyond high school
  • Anthropometrics:


Variable LWL Intervention Usual Care Total P
Weight (kg) 94.38±14.7 93.0±16.2 94.1±15.6 0.44
BMI (kg/m2) 32.8±3.9 32.6±4.1 32.7±4.0 0.54
Glucose (mg per dL) 105.4±12.5 105.7±10.0 105.5±11.3 0.79
Insulin (μU per ml) 16.7±9.7 16.7±10.0 16.7±9.8 0.95
HOMA-IR 4.4±3.0 4.4±2.9 4.4±2.9 0.99


Community around Wake Forest University/Wake Forest School of Medicine, Winston-Salem, North Carolina.


Summary of Results:

Key Findings

  • Over the first year of the intervention, participants attended 67.7% of all potential group intervention sessions. Including make-up visits (either in person or via telephone), participants completed 79.4% of all potential sessions.
  • Compared with usual-care participants, LWL intervention participants experienced significantly greater decreases in blood glucose (-4.3 vs. -0.4mg per dL), insulin (-6.5 vs. -2.7μU per ml), homeostasis model assessment of insulin resistance (-1.9 vs. -0.8), weight (-7.1 vs. -1.4kg), BMI (-2.1 vs. -0.3kg/m2) and waist circumference (-5.9 vs. -0.8cm).
 Variable  Baseline

Adjusted Means Over
the Follow-up Period

Weight (lb)   
     Control 92.67±1.37 92.12±0.29  
     Intervention 94.41±1.24 86.39±0.30  
     Difference   -5.73±0.42 <0.001
BMI (kg/m2)   
     Control 32.42±0.35 32.15±0.10  
     Intervention 32.81±0.34 30.25±0.10  
     Difference   -1.90±0.14  <0.001
Waist (cm)      
     Control 104.22±0.91 103.70±0.27  
     Intervention 104.83±0.79 98.65±0.27  
     Difference   -5.05±0.38  <0.001
Glucose (mg per dL)   
     Control  105.92±0.83  105.36±0.53  
     Intervention  105.58±1.07  101.60±0.54  
     Difference    -3.76±0.76  <0.001
Insulin (μU per ml)   
     Control  16.92±0.84 14.09±0.41  
     Intervention  16.73±0.82  10.34±0.41  
     Difference    -3.75±0.58  <0.001
     Control  4.50±0.24  3.73±0.12  
     Intervention  4.48±0.26  2.65±0.12  
     Difference    -1.08±0.17  <0.001
Percentage weight loss   
     Control  0.00±0.00  -1.25±0.31  
     Intervention  0.00±0.00  -7.37±0.31  
     Difference    -6.11±0.44  <0.001


Author Conclusion:
  • The HELP PD project was successful in translating the DPP LWL intervention into a community-based approach that induced significant reductions in blood glucose, insulin, and adiposity over 12 months in overweight and obese patients with prediabetes. Empowering community members through partnerships with existing DEPs may effectively translate diabetes prevention efforts.
  • Future analyses will examine the sustainability of the HELP PD effect over 24 months.
  • Limitations included:
    • Study was conducted in only one community located in the southeastern U.S.
    • A training program must be developed to prepare personnel
    • Reimbursement policies must be developed to support the cost of program delivery.
Funding Source:
Government: National Institute of Diabetes and Digestive and Kidney Diseases
Reviewer Comments:
  • The design, methods, recruitment procedures and participant characteristics have been described elsewhere, so some details omitted in this report
  • Unplanned treatment: New cases of diabetes requiring hypoglycemic medication.
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? ???
  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%.) No
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? ???
  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? 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? 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? No
  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)? 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