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MNT: Weight Management (2015)

Miller S, Oates V, Brooks M, Shintani A, Gebretsadik T, Jenkins D. Preliminary efficacy of group medical nutrition therapy and motivational interviewing among obese African American women with type 2 diabetes: a pilot study. Journal of Obesity, Volume 2014; 2014: 345941. PubMed ID: 25243082
Study Design:
Before-After Study
D - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
To assess the efficacy and acceptability of a group MNT intervention using motivational interviewing strategies (by trained diabetes educators and RDNs) among African-American women with type 2 diabetes mellitus.  
Inclusion Criteria:
  • At least 34 years of age
  • Type 2 diabetes diagnosis for at least six months
  • At risk for microvascular and macrovascular diabetes-related complications (HgbA1C, at least 7.0%) and either current SBP at or above 130mmHg, LDL of at least 100 or BMI of at least 30kg/m2.  
Exclusion Criteria:
Not described.
Description of Study Protocol:


Recruited from managed care organization and using radio, newspaper and e-mail ads.


One-arm interrupted time series design.


  • Dietitian-led group motivational interviewing (MI) activities consistent with MNT goals
  • Five group sessions included didactic education component, hands-on skill-building component with homework assignments and an MI component.

Statistical Analysis

Intervention efficacy (P-values in Table Three) was assessed via generalized least squares regression used to compare rate of change in outcomes quantified as the regression coefficient between pre- (baseline, 18, 12 and six weeks before intervention) and post-intervention (18, 12, and six weeks after intervention) phases to account for repeated measures.

Data Collection Summary:

Timing of Measurements

All assessments were administered at baseline and 18, 12 and six before and after intervention.

Dependent Variables

  • Self-care and psycho-social measures
    • Summary of diabetes self-care behaviors questionnaire to assess number of days per week engaged in specific dietary behaviors targeted during intervention (e.g., CHO spacing throughout the day, fruit-and-vegetable and fat intake and general eating behaviors)
    • Confidence in making food choices while dining out using a question from the Confidence in Diabetes Questionnaire.  
  • Physiological: Fasting blood draws for HgbA1C; blood pressure; BMI
  • Acceptability: Evaluation of program by participants assessed helpfulness, strengths, weakness of intervention components, previous exposure to information shared during didactic education component.

Independent Variables

Dietitian-led group MNT/Motivational Interveiwing Intervention.

Control Variables

Timing of measurements.

Description of Actual Data Sample:
  • Initial N: 24 females
  • Attrition (final N): *assumed to be 24
  • Age: 50.8±6.3 years
  • Ethnicity: African-American.

Other Relevant Demographics

  • 34% had an income of less than $10K
  • 43.4% work outside the home full time
  • Median type 2 diabetes mellitus duration of six years
  • 26.1% had vision problems
  • 50% had numbness in feet or legs.


  • BMI: 39±6.5 kg/m2
  • Hgb A1C: 8.8±2.0%.

Nashville, TN, USA.


Summary of Results:

Key Findings

  • HgbA1C: Significant increase (P=0.029) between post-intervention time-points, with levels returning to baseline. Non-significant changes in other physiologic outcome variables (e.g., BMI).
  • Increase in confidence choosing foods while dining out (P=0.055), which returned to baseline
  • Number of days per week eating fruit or vegetables increased (P=0.016) and decreased post-intervention
  • Number of days engaging in healthy diet increased over time (P=0.035) and decreased post-intervention
  • More than 95% of participants viewed each component as helpful and would recommend to other women.


18 Weeks rior to Intervention

Start of Intervention

6 Weeks Post-Intervention

18 Weeks Post-Intervention

Statistical Significance of Rate of Z Over Entire Study
18 weeks pre-intervention to 18 weeks post-intervention)

Eat Five Fruits or Vegetables (days/week)






Eat High-Fat Fried Food (days/week)






Eat a Generally Healthy Diet (days/week)





Confidence in Choosing Restaurant Foods (score) 1.9±0.9 2.05±0.8 2.1±0.9 1.8±0.6 0.055
BMI (kg/m2) 39±6.5 39.4±6.8 38.6±.5 38.9±6.8 0.407
HbA1c (%) 8.8±2.0 9.7±2.4 9.4±1.8 8.8±2.2 0.029



Author Conclusion:
Findings of this pilot trial support the potential efficacy of a dietitian-led group MNT/MI intervention in improving glycemic control and dietary self-care and warrant a full-scale RCT to evaluate the effectiveness of the intervention to promote improvements in diabetes psychosocial, self-care and clinical outcomes and to evaluate the relative influcence of different intervetnion components on outcomes of interest.  
Funding Source:
Government: NIH Grant R34DK090670
Reviewer Comments:
  • Paper states significant improvement in HgbA1c, but Table Three data cites an increase from 8.8% at Week -18 to 9.7% at Week Zero, back to 8.8% at week +18
  • Although improvements were noted in HbA1c, the values still exceed 7% recommended goal for glycemic control
  • No change in any other physiological outcomes (weightt, BMI, BP). 
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? No
  2.2. Were criteria applied equally to all study groups? N/A
  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? 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? Yes
  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? ???
  4.4. Were reasons for withdrawals similar across groups? N/A
  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? N/A
  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.) N/A
  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? No
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? No
  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? 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? 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)? No
  8.6. Was clinical significance as well as statistical significance reported? N/A
  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? N/A
  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