Health Disparities

HD: Effectiveness of Nutrition Intervention Methods (2010)


Vincent D, Pasvogel A, Barrera L. A feasibility study of a culturally tailored diabetes intervention for Mexican Americans. Biol Res Nurs. 2007 Oct; 9 (2): 130-141.

PubMed ID: 17909165
Study Design:
Group Randomized Trial
A - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

The purpose was to test the feasibility and examine the effects of a culturally-tailored intervention for Mexican Americans with type 2 diabetes.

Research Questions

  • Will Mexican American adults with type 2 diabetes agree to participate in a culturally-tailored diabetes program of three months' duration?
  • Will adults who participate have significantly better behavioral and biologic outcomes than a control group?
    • Behavioral outcomes: Diabetes knowledge,self-efficacy and self-management activities score
    • Biologic outcomes: Blood glucose, HbA1C, weight and body mass index
Inclusion Criteria:
  • Seen in a community health clinic in Tucson, Arizona
  • Self-identified Mexican-Americans
  • 18-75 years of age
  • Diagnosis of type 2 diabetes
  • Fluent in Spanish
  • Ability to walk without assistance.
Exclusion Criteria:
  • Pregnant
  • Medical condition in which dietary changes and exercise were contraindicated, such as heart failure
  • Cognitively impaired
  • Participated in a diabetes self-management program within the previous 12 months.
Description of Study Protocol:


  • Flyers posted in high-traffic areas within the clinic
  • Clinic providers and staff asked to refer prospective participants
  • A bilingual promotora (lay peer educator) contacted prospective participants using the clinic's diabetes roster.


Group randomized trial

Intervention Group

  • Eight weekly two-hour group sessions that included
    • Didactic content
    • Cooking demonstrations
    • Group support
  • Sessions held weekdays in clinic
  • Participants encouraged to bring a support person to sessions
  • Modeling accomplished through the use of the promotora and the cooking demonstration.

Control Group

  • Received usual care and education given by the clinic
    • 15-minute encounter with a physician or nurse practitioner two to four times per year
    • Pharmacological management is primary focus.

Statistical Analysis

  • Groups compared using independent samples T-tests and chi-square tests
  • Repeated measures analysis of covariance (ANCOVA) used for differences across time and between groups using education as a covariate
  • Repeated measures analysis of variance (ANOVA) was used for examining differences over time from baseline to three months between groups
  • Significance level set at P<0.05.


Data Collection Summary:

Timing of Measurements

  • Upon enrollment, baseline data collected
  • Biologic measures taken at baseline, at end of intervention (eight weeks) and four weeks post-intervention.

Dependent Variables

  • Behavioral outcomes
    • Diabetes knowledge: Using Diabetes Knowledge Questionnaire Spanish version (Garcia et al., 2001)
    • Self efficacy: Self-Efficacy for Diabetes Scale, Spanish Version (Lorig, Ritter, & Gonzales, 2003)
    • Self-management activities: Summary of Diabetes Self-Care Activities revised (SDSCA) measure (Toobert, Hampson, & Glasgow, 2000).
  • Biologic outcomes
    • Blood glucose
    • HbA1c
    • Weight
    • BMI.
  • Feasibility
    • Ability to recruit target number of participants
    • Achieve a 70% retention rate.

Independent Variables

  • Level of acculturation, assessed using the Short Acculturation Scale for Hispanics (SASH)
  • Age
  • Gender
  • Marital status
  • Years of formal education
  • Income
  • Number of years diagnosed with diabetes.

Control Variables


Description of Actual Data Sample:
  • Initial N: 20 ( 71% female)
  • Attrition (final N): 17 (eight, control group; nine, intervention group)
  • Age: Mean age 56, (SD=9.3, range 37-69)
  • Ethnicity: Mexican American
  • Other relevant demographics:
    • 50% married
    • Mean time since diagnosis was 7.9 years
    • 76% reporting an income of less that $20,000 a year (low socioeconomic status)
    • No participants had participated in a previous study in the past 12 months.
  • Group Differences
    • 89% of intervention group was female, 50% of the control group (P=0.08)
    • Intervention group has 6.4 years of education, control group had 13.1 years of education (P=0.01).
  • Location: Tucson, Arizona.


Summary of Results:

Key Findings

  • Significant decrease in weight for intervention group over time
  • Significant decrease in BMI for intervention group over time
  • Significant change in blood glucose for intervention group over time, decreased during intervention, increased four weeks post-intervention
  • Self-management activities improved for the intervention group
    • Significant group-by-time interaction for self-management activities related to blood glucose P=0.00
    • Significant increase in self-management activities scores from baseline to end of the intervention, then a slight decrease at four weeks post-intervention
    • Significant change over time in scores for self-management activities related to exercise, P=0.002.
  • Self-management activities increased significantly for the control group from baseline to end of intervention and was maintained at four weeks post-intervention
    • Scores for self-management activities related to diet changed over time, P=0.002.
Intervention Group Baseline * Post-intervention*  Four weeks Post-intervention* 

Weight (lbs)

175.50 (19.5) 172.78 (17.7) 170.56 (16.1)
BMI 30.62 (2.7) 30.16 (2.2) 29.76 (1.9)
Blood glucose 173.11 (60.7) 121.44 (37.1) 150.00 (39.9)
Self-management activities 3.37 (1.0) 5.73 (0.7) 4.97 (0.7)

blood glucose

0.67(1.4) 6.69 (0.9) 4.72 (2.6)
exercise 2.84 (1.8) 5.25 (2.2) 5.11 (1.8)


(control group only)

3.78 (1.3) 4.25(1.0) 5.02(1.2)

 *Measurements reported as mean and standard deviation, m (SD)

Other Findings

  • Met retention rate (85%) for study feasibility
  • Most successful recruitment strategy was personal phone calls made by promotora
  • Weekly telephone reminders from the promotora were successful for participant retention.


Author Conclusion:
  • Study achieved recruitment and retention goals
  • The intervention had positive clinical and statistical effects on the outcome measures of diabetes knowledge, weight and BMI.
Funding Source:
University/Hospital: University of Arizona College of Nursing
Reviewer Comments:
  • No blinding used in study
  • Lack of difference seen between groups may be due to small sample size
  • P-values not given for many results that were described as significant
  • Well-written feasibility study and should influence future studies in this area.
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? No
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) N/A
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? No
  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")? No
4. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? N/A
  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? Yes
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.) No
  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? No
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? 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? Yes
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? No
  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? No
  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)? No
  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