GDM: Introduction (2016)

Guideline Overview

Guideline Title

Gestational Diabetes (2016) Evidence-Based Nutrition Practice Guideline

Guideline Narrative Overview

The focus of this guideline is on nutrition practice during the treatment of women with gestational diabetes mellitus (GDM). According to the American Diabetes Association (ADA), “GDM is diabetes diagnosed in the second or third trimester of pregnancy that is not clearly either type 1 or type 2 diabetes (ADA, 2016)." All pregnant women are generally tested for GDM between 24-28 weeks of gestation, [American College of Obstetricians and Gynecologists (ACOG), 2013] if they have not previously been diagnosed with overt diabetes. Screening and diagnosis of GDM may be made by one of two strategies at 24-28 weeks of gestation:

One-step strategy

Perform a 75g oral glucose tolerance test (OGTT), with plasma glucose measurement when patient is fasting and at 1 and 2 hours. The OGTT should be performed in the morning after an overnight fast of at least 8 hours. A GDM diagnosis is made when any of the following plasma glucose values are met or exceeded:

Time	Criteria
Fasting	92 mg/dL (5.1 mmol/L)
1 h	180 mg/dL (10.0 mmol/L)
2 h	153 mg/dL (8.5 mmol/L)

Two-step strategy

Step 1: Perform a 50g glucose load test (GLT) (nonfasting), with plasma glucose measurement at 1 hour. If the plasma glucose level measured 1 hour after the load is ≥140 mg/dL* (7.8 mmol/L), proceed to a 100g OGTT. [Note: *The ACOG recommends 135mg/dL (7.5mmol/L) in high-risk ethnic populations with higher prevalence of GDM; some experts also recommend 130mg/dL (7.2 mmol/L).]

Step 2: The 100g OGTT should be performed when the patient is fasting. A GDM diagnosis is made if at least two of the following four plasma glucose levels (measured fasting and 1 h, 2 h, 3 h after the OGTT) are met or exceeded:

Time	Carpenter/Coustan		National Diabetes Data Group
Fasting	95 mg/dL (5.3 mmol/L)	OR	105 mg/dL (5.8 mmol/L)
1 h	180 mg/dL (10.0 mmol/L)	OR	190 mg/dL (10.6 mmol/L)
2 h	155 mg/dL (8.6 mmol/L)	OR	165 mg/dL (9.2 mmol/L)
3 h	140 mg/dL (7.8 mmol/L)	OR	145 mg/dL (8.0 mmol/L)

The above One-Step and Two-Step Strategies were adapted from Table 2.5—Screening for and diagnosis of GDM (ADA, 2016). Refer to ADA, 2016 for more information on diagnosis of GDM.

Pregnant women who have risk factors for GDM (e.g., prior history of GDM, obesity, known impaired glucose metabolism) are screened earlier in the pregnancy for undiagnosed type 2 diabetes (ACOG, 2013; ADA, 2016).

Pregnant women with GDM are at increased risk for maternal and fetal complications, including preeclampsia, fetal macrosomia (which can cause shoulder dystocia and birth injury), and neonatal hypoglycemia. In addition, women are at increased risk of maternal diabetes after delivery (ADA, 2016).

Lifestyle modification through medical nutrition therapy (MNT) and physical activity are cornerstones of GDM treatment. Often weight management (in women who are overweight or obese at conception), and pharmacologic therapy are also indicated (ADA, 2016).
“It is the position of the Academy of Nutrition and Dietetics that women of childbearing age should adopt a lifestyle optimizing health and reducing risk of birth defects, suboptimal fetal development, and chronic health problems in both mother and child. Components leading to healthy pregnancy outcome include healthy prepregnancy weight, appropriate weight gain and physical activity during pregnancy, consumption of a wide variety of foods, appropriate vitamin and mineral supplementation, avoidance of alcohol and other harmful substances, and safe food handling (Kaiser & Campbell, 2014)."

It is within this context of nutrition and lifestyle for a healthy pregnancy outcome, that a more delicate balance is needed for women with GDM, in order to achieve and maintain blood glucose targets, weight gain targets, and prevent adverse maternal and fetal outcomes. The individualization of the composition of the diet, in terms of calories and amount, type, and distribution of macronutrients plays a critical role in this balance, as the research demonstrates that a variety of dietary interventions/patterns may be beneficial in the treatment of GDM. There is no “one size fits all” approach to diet for every woman with GDM.

References:
American Diabetes Association (ADA). Classification and diagnosis of diabetes. Sec. 2. In Standards of Medical Care in Diabetes 2016. Diabetes Care 2016; 39 (Suppl. 1): S13–S22.

American College of Obstetricians and Gynecologists (ACOG). Committee on Practice Bulletins--Obstetrics. Practice Bulletin No. 137: Gestational diabetes mellitus. Obstet Gynecol. 2013 Aug;122 (2 Pt 1):406-416. doi: 10.1097/01.AOG.0000433006.09219.f1. PMID: 23969827.

Kaiser LL, Campbell CG; Academy Positions Committee Workgroup. Practice paper of the Academy of Nutrition and Dietetics abstract: nutrition and lifestyle for a healthy pregnancy outcome. J Acad Nutr Diet. 2014 Sep;114 (9):1, 447. PMID: 25699300.

Guideline Development

The recommendations in this guideline were based upon a systematic review of the literature and the work performed by the Academy of Nutrition and Dietetics Expert Work Group on GDM. In addition, recommendations were supplemented by two external guidelines, whose methodology was approved the Academy's Evidence-Based Practice Committee (EBPC). These include guidelines from:

American Diabetes Association
The Endocrine Society.

To view the guideline development and review process, see Guideline Methods.

The recommendations provide a framework for the registered dietitian nutritionist (RDN) to successfully integrate individualized medical nutrition therapy (MNT) into the overall medical management of women with GDM. Topics include:

Referral to an RDN
Nutrition Assessment
MNT
Calories
Macronutrients
Vitamins and Minerals
Meal and Snack Distribution
High-Intensity Sweeteners
Alcohol
Physical Activity
Nutrition Monitoring and Evaluation.

Contributors

Expand the Project Team to see the list of expert workgroup members, analysts, and contributors for this project.

Revision

Academy guidelines are revisited every five years. A scoping review will be conducted to examine the need for new and revised recommendations based on the available science. The process includes:

Literature searches and evidence scoping to identify new research published since the previous searches were completed. Updated inclusion/exclusion criteria and search terms may be warranted.
Council on Research review to determine if the update will inlcude modification to all, some or no recommendations compared to the earlier version(s) of the guideline, or development of new recommendations.
Creation of a table comparing the new guideline and the older version of the guideline. The document will indicate which recommendations remained unchanged; updated, new; or not reviewed.

Using the Academy's EAL process, an unbiased and transparent systematic review will be completed and the updated guideline published on the EAL. To learn more about the Academy's development process, download "Academy of Nutrition and Dietetics Methodology for Developing Evidence-Based Nutrition Practice Guidelines. J Acad Nutr Diet 2017 May 117; (5):794-804.

Medical Nutrition Therapy and Gestational Diabetes Mellitus

Scientific evidence supports the importance of the RDN providing MNT to women with GDM and is integral to the interdisciplinary health care team caring for women with GDM.

The RDN designs the optimal nutrition care plan and prescription that complements physical activity, self-management, and pharmacologic therapy, if needed. Based on the patient’s clinical status, plan for treatment, and comorbidities, the RDN monitors and evaluates the effectiveness of the nutrition care plan in promoting the patient’s nutrition and health outcomes. The RDN adjusts the nutrition care plan as necessary to achieve desired outcomes.

Populations to Whom This Guideline May Apply

This guideline applies to adult pregnant women with GDM.

Other Guideline Overview Material

For more details on the guideline components, select the topics below from the introduction in the left navigation bar:

Scope of Guideline
Statement of Intent and Patient Preference
Guideline Methods
Implementation of the Guideline
Benefits and Harms of Implementing the Recommendations.

Contraindications

This guideline was developed for adult women, who are diagnosed with GDM. This guideline is not intended for pregnant women with pre-existing diabetes (type 1 or 2), undiagnosed type 2 diabetes, or women who are at risk for developing GDM (without diagnosis of GDM). Therefore, clinical judgment is crucial in the application of these guidelines for individuals other than adult women with GDM.

This guideline is not intended:

For interventions typically within the scope of practice of a certified exercise physiologist or other professional, for which, adequate training in physical activity interventions and other therapies is necessary.
As a replacement for interventions typically within the scope of practice of an athletic trainer or behavioral or psychological professional, for which adequate training in physical activity interventions or behavioral therapy is necessary.
Preconception nutrition guidance for prevention of GDM
For postpartum prevention of diabetes
To address factors influencing recurrence of GDM or progression to type 2 diabetes

The reader may explore other EAL Guidelines such as Diabetes 1 and 2, Prevention of Type 2 Diabetes or Adult Weight Management or systematic review projects, such as Breastfeeding, Nutrition Counseling, or Obesity, Reproduction, and Pregnancy for further information on treatment beyond this guideline.