GDM: Medical Nutrition Therapy (2016)

Perichart-Perera O, Balas-Nakash M, Parra-Covarrubias A, Rodriguez-Cano A, Ramirez-Torres A, Ortega-Gonzalez C, and Vadillo-Ortega F. A Medical Nutrition Therapy Program improves perinatal outcomes in Mexican pregnant women with gestational diabetes and type 2 Diabetes Mellitus. The Diabetes Educator. 2009: 35 (6), 1,004-1,013.


PubMed ID: 19696205
Study Design:
Non-Randomized Controlled Trial
C - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
To assess the effect of a medical nutrition therapy (MNT) program on maternal, fetal and neonatal complications with different types of diabetes (DM) in pregnant women in Mexico City.
Inclusion Criteria:
  • Gestational age less than 29 weeks
  • Diagnosis of gestational diabetes sub-class A2, gestational diabetes sub-class B1 or pre-gestational type 2 diabetes mellitus
  • Aminimum of two serum fasting and two hours post-prandial glucose values
  • Planning to receive care from the study institution
  • Informed consent was given by the patients.
Exclusion Criteria:
  • Gestational diabetes sub-class A1
  • Type 1 DM
  • Renal, hepatic or thyroid disorders
  • DM complications.
Description of Study Protocol:

The pregnant women in the Intervention Group were screened in the Endocrinology Department from 2004 to 2006, whereas the women in the Control Group were selected from the medical charts of the same department from 2001 to 2003 and included in the study by sequential order to obtain a comparable sample.

Quasi-experimental design with historical controls.

Blinding Used
Not mentioned.


  • MNT program including individualized counseling with an intensive education component
  • Specific materials were designed for MNT and self-monitoring education
  • The MNT program included nutrition assessment, nutrition intervention and capillary glucose self-monitoring
  • Nutrition recommnedations were based on nutrition practice guidelines for gestational diabetes from AND
  • The diet strategy was to provide carbohydrates between 40% and 45% of total calories and moderate energy restriction of no less than 1,700kcal per day

Statistical Analysis

  • Power analysis of 80% was conducted and a minimum sample of 44 women was required for each group
  • Chi-square test and Fisher's test with a significant difference of P<0.05
  • Multivariate regression analysis: Odds ratio, 95% CI.
Data Collection Summary:

Timing of Measurements

  • Intervention Group
    • Fasting and two hours post-prandial serum glucose were measured every two weeks and capillary blood glucose was self-monitored two days per week, six times per day (before and two hours after each meal)
    • Ketonuria and maternal weight were measured on each visit and all women received follow-up every two weeks until delivery
    • Diet was assessed monthly
    • Pre-gestational weight was self-reported and BMI calculated
  • Control Group
    • Women received usual routine care for pregnant women including a visit with an endocrinologist every two weeks after 28 weeks
    • Most of them attended one initial nutrition orientation group session headed by a technician
    • Data of pre-gestational weight, BMI, diet and capillary blood glucose were not available in this group.

Dependent Variables

  • Pre-eclampsia
  • Maternal hospitalization (first and subsequent hospitalization rate)
  • Intra-uterine death
  • Neonatal death
  • Macrosomia
  • Prematurity
  • Low birth weight (LBW)
  • Neonatal intermediate care unit.

Independent Variables

Medical Nutrition Therapy Program.

Control Variables

  • Gestational age
  • History of miscarriages
  • Parity
  • Number of women using insulin at baseline
  • Previous comorbid conditions.
Description of Actual Data Sample:
Initial N
  • Intervention Group: 108
  • Control Group: 86.
Attrition (Final N)
  • 88: 49 type T2DM; 39 GDM (Intervention Group)
  • Reasons for drop-out: 18 unable to have four or more visits with the dietitian; two had deliveries elsewhere
  • 86: 47 T2DM; 39 GDM (Control Group).
  • Mean: 32.3 years (both groups)
  • Range: Intervention Group, 22 to 42 years; Control Group, 19 to 43 years.


Other Relevant Demographics

At baseline, T2DM women in the Intervention Group used more insulin compared to the Control Group (91.5% vs. 55.3%), but GDM in the Control Group used more insulin than the Intervention Group (56.4% vs. 35.9%).


In the Intervention Group, 50% of the women were obese and aproximately 39% were overweight.


Mexico City, Mexico.

Summary of Results:

Key Findings

  • Total perinatal complications was higher in the Control Group, compared to the MNT program (P=0.005)
  • Fewer women developed pre-eclampsia in the MNT Group, compared to the Control Group: 2.3% vs. 16.3%; P=0.001
  • First maternal hospitalization due to uncontrolled hyperglycemia was less frequent in women in the MNT program, compared to Control Group: 5.7% vs. 62.8%; P<0.001
  • Lower neonatal intensive care unit (NICU) admission was lower in the MNT Group, compared to the Control Group: 25.9 vs. 51.2; P=0.01
  • Lower NICU admission was observed among women with T2DM in the MNT program, compared to the Control Group (28.2 vs. 66.0; P<0.001)
  • In the MNT program, T2DM women showed lower risk of pre-eclampsia after adjusting for gestational age, number of previous miscarriages, parity and the number of women using insulin at baseline: OR, 0.066; CI, 0.06 to 0.71; P≤0.02
  • After adjusting for the confounding factors, a decrease in LBW was observed in the GDM Group participating in the MNT program: OR, 0.12; CI, 0.01 to 0.94; P=0.030 
  • No neonatal deaths were observed among women in the MNT Group and intra-uterine death was similar between MNT and Control Groups
  • The MNT program showed a trend of lower rates in the frequency of prematuriy, macrosomia and LBW.

Other Findings
Carbohydrate and other macronutrients intake at baseline and after MNT in the MNT program

Time Carbohydrates Protein Fat Calories
Kcal per day
Baseline 48.06% 21.33% 32.24% 1,495±429.22
After MNT 47.20% 24% 30.7% 1,505±299.97
Author Conclusion:
  • An intensive MNT program (including counseling, education and capillary glucose self-monitoring) had a positive effect on pre-enclampsia, maternal hospitalization and neonatal death in women with diabetes in pregnancy
  • The program also reduced the risk of LBW in women with GDM and NICU admission in women with T2DM.
Funding Source:
Reviewer Comments:
Authors limitations comments
  • The comparison with retrospective secondary data and bias may be a problem
  • NICU admission criteria for newborns of diabetic mothers changed over the years, increasing a confounding effect on the observations
  • Lack of information about the type of nutrition practice given to the Control Group in the past and its impact on the perinatal outcomes
  • Small sample size for some outcomes such as macrosomia.
Results may be only aplicable to the women who were compliant to the diet and only Mexicans, once those who dropped out of the MNT program were not included in the analysis.
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? No
  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? No
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) No
  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? ???
  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? ???
  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? ???
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? ???
  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? N/A
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? N/A
  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? No
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? No
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