MNT: Disorders of Lipid Metabolism (2015)


Parker AR, Byham-Gray L, Denmark R, Winkle PJ. The Effect of Medical Nutrition Therapy by a Registered Dietitian Nutritionist in Patients with Prediabetes Participating in a Randomized Controlled Clinical Research Trial. J Acad Nutr Diet. 2014. doi:10.1016/j.jand.2014.07.020.

PubMed ID: 25218597
Study Design:
Randomized Controlled Trial
A - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:
To investigate the effect of MNT compared to usual care (UC) on fasting plasma glucose values, glycated hemoglobin, serum lipid levels and Diabetes Risk Score, from baseline to the end of the 12-week intervention in overweight or obese adults with prediabetes.
Inclusion Criteria:
  • Aged 18 years or older
  • With IFG (more than 100mg per dL) or HbA1c between 5.7% and 6.4%
  • BMI of 25kg/m2 or higher
  • No previuos histroy or treatment for type 2 diabetes
  • Not regularly active (30 minutes per day on five days per wk of moderate-intensity physical activity).
Exclusion Criteria:
  • Type 2 diabetes or use of anti-diabetic medications
  • Concomitant medications known to interfer with glucose metabolism
  • Use of weight loss drugs
  • Pregnancy or breastfeeding
  • Refusal or inability to give informed consent
  • Hospitalized for heart disease, stroke or transient ischemic attach during the past six months
  • Mental incapacity, unwillingness or language barrier precluding understanding or cooperation.
Description of Study Protocol:


  • Participants were referred by physicians at Anaheim Clinical Trials or responded to Internet advertising and flyers distributed in the clinic waiting rooms
  • Recruitment occured between April 2010 and May 2011.


  • Randomized control trial comparing control (usual care and only baseline and 12-week assessment) and MNT intervention
  • Participants were screened and then randomized to either control or MNT intervention
  • Anthropometric and clinical measures were taken and participants completed the Diabetes Risk questionnaire.


  • Participants received four MNT visits in a 12-week period with an RD, based upon the American Diabetes Association Standards of Medical Care
  • Visit Two was 60 minutes of individualized care by a RD in which participants provided a 24-hour dietary recall and receiving a pedometer and diary (recording steps per day and minutes of physical activity)
  • Participants had three 30- to 45-minute additional visits with an RD focused on emphasizing lifestyle change to promote moderate weight loss (5% to 7% of initial weight; one to two pounds per week), regular exercise (150 minutes per week at 50% to 70% maximum heart rate) and provided strategies to reduce calories and dietary fat
  • Diet consisted of 60% to 70% of energy as carbohydrate and MUFA, 15% to 20% protein, less than 7% SFA and minimized trans fats
  • Participants were encouraged to consume whole grains and achieve 14g fiber per 1,000 kcal and limit alcohol to moderate consumption (one drink per day for women, two drinks per day for men)
  • Participants also recieved a Exchange list of foods for diabetes.

Statistical Analysis

  • Factorial repeated-measures analysis of variance using SPSS v19 to compare FPG, HbA1c, total cholesterol, LDL-cholesterol, HDL-cholesterol, TG, Diabetes Risk Score and DRC from baseline to 12 weeks
  • Sample size estimated at N=60 total based upon 0.25 effect size for primary variable (glucose) at alpha of 0.5 and 95% power with 20% possible attrition.
Data Collection Summary:

Timing of Measurements - Baseline and 12 weeks

Dependent Variables (did not describe methods for each outcome except DRS)

  • BMI
  • Fasting plasma glucose (FPG)
  • Glycated Hemoglobin (HbA1c)
  • Total cholesterol
  • HDL-c
  • LDL-c
  • Triglycerides
  • Diabetes Risk Score (DRS) - based on diabetes risk factors (BMI, WC, Family hx T2DM); hx high FBG; physical activity; daily consumption of fruits, vegetables and berries). Scores range from 0-20 pts with score of 9 or more at higher risk of developing T2DM in next 10 yrs
  • Diabetes Risk Calclulator (DRC) - questions on age, WC, hx of gestational DM, Ht, race/ethnicity, HTN, family hx, and exercise. 

Independent Variables - Time and group

Control Variables - None noted


Description of Actual Data Sample:

Initial N: 81 (20 M, 61 F); 43 MNT and 38 control

Attrition (final N): 76; 93% completed

Age: 51.1 ± 12.4 yrs MNT; 49.6 ± 15.6 yr UC

Ethnicity: 83% White (37% Hispanic/Latino), 17% Asian; 85% with family hx of T2DM; 62% with HTN; 89% with HLD; 35% overweight / 65% obese.

Other relevant demographics: Patients of Anaheim Clinical Trials

Anthropometrics - no significant differences identifiied between groups
BMI: 34.2 ± 6.2 kg/m2 MNT; 33.1 ± 6.3 kg/m2?;
Waist circumference: 108.4 ± 14.4 cm MNT; 

Location: Anaheim, CA and nearby commuities 

Summary of Results:

Key Findings - Change in Health Outcome measures (0-12 wks)

Variable UC (n=35) MNT (n=41) p-value
FPG (mg/dl) -1.97 ± 17.7 -1.66 ± 17.2 0.94
HbA1c (%) 0.05 ± 0.36 -0.19 ± 0.41 0.01
Total Chol (mg/dl) -3.69 ± 26.14 -10.22 ± 21.58 0.24
HDL-chol (mg/dl) 1.23 ± 5.4 -0.02 ± 6.88 0.39
LDL-chol (mg/dl) -4.46 ± 31.87 -8.73 ± 21.58 0.49
Triglyceride (mg/dl) -9.00 ± 63.49 -6.98 ± 40.89 0.87
Diabetes Risk Score -0.40 ± 2.03 -2.22 ± 2.03 <0.001
Diabetes Risk Calculator -0.13 ± 5.00 -1.64 ± 4.43 0.11

Significant improvement in HbA1c and Diabetes Risk Score in MNT compared to UC group.

Other Findings

  • As noted by significant changes in table above, there was an interaction effect for HbA1c  (F=7.36; P=0.01; partial n2=0.09) showing a different group effect for time. The interaction effect for Diabetes Risk Score was significant (F=12.26; P<0.001; partial n2=0.14).
  • 95% of MNT and 43% of UC reported 30-min or more of mod-physical activity at 12 wks.
  • Within subjects main effect for total cholesteral (F=6.45; P=0.01, partial n2=0.08) and LDL choleterol (F=4.57; P=0.04, partial n2=0.06) were significant independent of group assignment.
  • Results were not significant for FPG, HDL-c, TG, or DRC.
Author Conclusion:
MNT following practice guidelines can lead to improvement in metabolic control in diabetes patients (espeically in HbA1c and DRS improvements). Beneficial medial outcomes from MNT may prevent or delay the onset of T2DM. Further research is needed to include a longer intervention period with multiple site involvement.
Funding Source:
Diabetes Care and Education Dietetic Practice Group / Academy of Nutrition and Dietetics Foundation Diabetes MNT Outcomes Research Award
Reviewer Comments:
Several limitations noted by the authors: 12-wk is relatively short intervention to draw conclusions; several confounders could influence results (income, attitudes, practice site, etc.). 
Reviewer noted: small sample size and no description of UC (appeared to only involve baseline and 12 wk assessment without any treatment).
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? N/A
  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? 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? 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? 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? 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? N/A
  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? ???
  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)? 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