DASH (2016)


Asemi Z, Tabassi Z, Samimi M, Fahiminejad T. Favorable effects of the Dietary Approaches to Stop Hypertension diet on glucose tolerance and lipid profiles in gestational diabetes: a randomised clinical trial. Br J Nutr. 2013 Jun; 109(11): 2,024-2,030.

PubMed ID: 231488885
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 investigate the effects of the DASH eating plan on glucose tolerance and lipid profiles of pregnant women with gestational diabetes mellitus.
Inclusion Criteria:
  • Pregnant women 
  • Aged 18 to 40 years
  • Diagnosed with GDM by a 100g oral glucose tolerance test at 24 to 48 weeks of gestation
  • Pregnant women with one-hour plasma glucose concentrations of more than 7.77mmol per L (1,400mg per L) were asked to participate in a 100g glucose tolerance test
  • Diagnosis of GDM was based on the criteria set by the American Diabetes Association and those in whom the plasma glucose levels met two of the following criteria were considered as having GDM: fasting more than 5.27mmol per L (950mg per L), one hour greater than or equal to 9.99mmol per L, two hours greater than or equal to 860mmol per L (1,550mg per L) and three hours greater than or equal to 7.77mmol per L (1,400mg per L).
  • Provided written informed consent
Exclusion Criteria:
  • Those with untreated hypothyroidism, smoking and kidney or liver diseases
  • Those taking estrogen therapy.
Description of Study Protocol:


Pregnant women were recruited from maternity clinics affiliated to the Kashan University of Medical Sciences, Kashan Iran.


Randomized controlled trial.

Statistical Analysis

  • To ensure the normal distribution of variables, histogram and Kolmogrov-Smirnov tests were applied
  • The independent samples Student's T-test was used to detect differences in general characteristics and dietary intakes between the two groups
  • To determine the effect of the DASH diet on metabolic profiles, repeated measured ANOVA where treatment x time interactions were treated by using Pillai's trace
  • P<0.05 was considered as statistically significant
  • All analyses were done using the Statistical Package for Social Science version 17 (SPSS, Inc.).


Data Collection Summary:

Timing of Measurements

Fasting blood samples were taken at baseline and after four weeks of intervention to measure:
  • Fasting plasma  glucose
  • Glycated Hb (HbA1c)
  • Lipid profiles.

Dependent Variables

Glucose tolerance: Women underwent a three-hour oral glucose tolerance test; blood samples were collected at 60, 120 and 180 minutes to measure plasma glucose levels. 

Independent Variables

DASH diet: Diet was rich in fruits, vegetables, whole grains and low-fat dairy products and contained lower amounts of saturated fats, cholesterol and refined grains with a total of 2,400mg Na per day, consumed for four weeks.

Control Variables

Control diet for 4 weeks, which consisted of:
  • 45% to 55% carbohydrates
  • 15% to 20% protein
  • 25% to 30% total fat.
Description of Actual Data Sample:
  • Initial N: 45 women assessed for eligibility
  • Attrition (final N): 34 analysed
  • Age: Mean age of those women in the control group (29.4 years) vs. 30.7 years in the DASH diet group
  • Other relevant demographics: Mean pre-pregnancy weight 75.5kg in the control group vs. 67.4kg in the DASH diet group
  • Anthropometrics: Mean BMI in controls 29.6 vs. 26.7 in those randomized to the DASH diet group
  • Location: Iran.


Summary of Results:

Key Findings

  • Adherence to the DASH diet eating pattern, compared with the control diet, resulted in improved glucose tolerance such that plasma glucose levels reduced at 60 (-1.86 vs. -0.45mmol per L, P=0.02), 120 (-2.3 vs. 0.2mmol per L, P=0.001) and 180 minutes (-1.7 vs. -.22mmol per L, P=0.002) after the glucose load
  • Decreased HbA1c levels (-0.2 vs. 0.05%, P=0.001) was also seen in the DASH group compared with the control group
  • Mean changes for serum total cholesterol (-0.42 vs. 0.31mmol per L, P group=0.01) and LDL-cholesterol (-0.47 vs. 0.22mmol per L, P=0.005), TAG (-0.17 vs. 0.34mmol per L, P=0.01) and total:HDL-cholesterol ratio (-0.6 vs. 0.3, P=0.008) were significantly different between the two diets
  • DASH diet favorably influenced systolic blood pressure (-2.6 vs. 1.7mm Hg, P=0.001)
  • There were no significant differences in energy intake between the two groups, but there were significant differences between groups in regards to intake of saturated fatty acids, polyunsaturated fatty acids, dietary fiber, cholesterol, simple sugars, sodium and potassium (P<0.05 for all).
Author Conclusion:
Consumption of the DASH eating pattern for four weeks among pregnant women with GDM results in beneficial effects on glucose tolerance and lipid profiles compared with a control diet.
Funding Source:
Other: Grant (no. 9013) from the VIce-chancellor for Research, KUMS, Kashan, Iran
Reviewer Comments:
One of the limitations of the present study is the duration of this trial, also the investigators were unable to administer the diets for more than four weeks due to the particular condition of the pregnant women.
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? No
  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) 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? 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? Yes
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? Yes
  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? 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)? No
  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? 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