CMECNE

Screening for Gestational Diabetes: The ‘2 Step’ Approach

Learning Objectives and CME/Disclosure Information

This activity is intended for healthcare providers delivering care to women and their families.

After completing this activity, the participant should be better able to:

1. Explain why screening all women for GDM rather than only those with risk factors is appropriate
2. Assess a patient for risk factors for gestational diabetes that should prompt and early screening in pregnancy

Estimated time to complete activity: 0.25 hours

Faculty:

Susan J. Gross, MD, FRCSC, FACOG, FACMG
President and CEO, The ObG Project

Disclosure of Conflicts of Interest

Postgraduate Institute for Medicine (PIM) requires instructors, planners, managers and other individuals who are in a position to control the content of this activity to disclose any real or apparent conflict of interest (COI) they may have as related to the content of this activity. All identified COI are thoroughly vetted and resolved according to PIM policy. PIM is committed to providing its learners with high quality CME activities and related materials that promote improvements or quality in healthcare and not a specific proprietary business interest of a commercial interest.

Faculty: Susan J. Gross, MD, receives consulting fees from Genoox, Inc., and has financial interest in The ObG Project, Inc.

Planners and Managers: The PIM planners and managers, Trace Hutchison, PharmD, Samantha Mattiucci, PharmD, CHCP, Judi Smelker-Mitchek, MBA, MSN, RN, and Jan Schultz, MSN, RN, CHCP have nothing to disclose.

Method of Participation and Request for Credit

Fees for participating and receiving CME credit for this activity are as posted on The ObG Project website. During the period from Dec 31 2017 through Dec 31 2020, participants must read the learning objectives and faculty disclosures and study the educational activity.

If you wish to receive acknowledgment for completing this activity, please complete the post-test and evaluation. Upon registering and successfully completing the post-test with a score of 100% and the activity evaluation, your certificate will be made available immediately.

For Pharmacists: Upon successfully completing the post-test with a score of 100% and the activity evaluation form, transcript information will be sent to the NABP CPE Monitor Service within 4 weeks.

Joint Accreditation Statement

In support of improving patient care, this activity has been planned and implemented by the Postgraduate Institute for Medicine and The ObG Project. Postgraduate Institute for Medicine is jointly accredited by the Accreditation Council for Continuing Medical Education (ACCME), the Accreditation Council for Pharmacy Education (ACPE), and the American Nurses Credentialing Center (ANCC), to provide continuing education for the healthcare team.

Physician Continuing Medical Education

Postgraduate Institute for Medicine designates this enduring material for a maximum of 0.25 AMA PRA Category 1 Credit(s)™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Continuing Nursing Education

The maximum number of hours awarded for this Continuing Nursing Education activity is 0.2 contact hours.

Read Disclaimer & Fine Print

CLINICAL ACTIONS:

Professional organizations agree that all pregnant women should be screening for Gestational Diabetes Mellitus (GDM). While there are varying approaches, ACOG and a consensus panel convened by the NIH have endorsed the following ‘2 step’ approach to screening for GDM:

STEP 1: All women should be screened for GDM between 24 and 28 weeks gestation with a 50g oral glucose solution followed by a 1 hour venous glucose measurement. Healthcare providers have the option of using the following values:

130 or 135 mg/dL – lower cut-off threshold – which may identify women who may have GDM but also increase false positive rates
140 mg/dL – higher cut-off threshold – which may limit the number of screen positive women, but may miss those with GDM

Screen earlier in pregnancy if high risk factors for GDM are identified:

Patient is overweight with BMI of 25 (23 in Asian Americans) and one of the following:

Physical inactivity
Known impaired glucose metabolism
Previous pregnancy history of:
- GDM
- Macrosomia (≥ 4000 g)
- Stillbirth
Hypertension (140/90 mm Hg or being treated for hypertension)
HDL cholesterol < 35 mg/dl (0.90 mmol/L)
Triglyceride > 250 mg/dL (2.82 mmol/L)
PCOS
Hgb A_1C ≥ 5.7%, impaired glucose tolerance or impaired fasting glucose
Cardiovascular disease
Signs/symptoms suggesting increased risk for diabetes such as acanthosis nigricans or morbid obesity)
Family history of diabetes – 1st degree relative
Ethnicity of African American, American Indian, Asian American, Hispanic, Latina, or Pacific Islander

If a patient with risk factors is tested earlier and is screen negative, the patient should still be screened again between 24-28 weeks using the 50g oral glucose load.

STEP 2: If screen positive following STEP 1, a diagnostic test, the 100g 3 hour oral glucose tolerance test (OGTT), is recommended. A diagnosis is made if at least two values are exceeded using one of two methods:

Note: In new ACOG guidelines, due to increased complications with even a single elevated abnormal value, 1 abnormal value may be used to diagnose GDM.

National Diabetes Data Group

Fasting ≥ 105 mg/dL (5.8 mmol/l)
1-hour ≥ 190 mg/dL (10.6 mmol/l)
2-hour ≥ 165 mg/dL (9.2 mmol/l)
3-hour ≥ 145 mg/dL (8.0 mmol/l)

Carpenter and Coustan

Fasting ≥ 95 mg/dL (5.3 mmol/l)
1-hour ≥ 180 mg/dL (10.0 mmol/l)
2-hour ≥ 155 mg/dL (8.6 mmol/l)
3-hour ≥ 140 mg/dL (7.8 mmol/l)

Note: The ADA has removed the National Diabetes Data Group from its guidelines and recognizes ‘2 step’ Carpenter and Coustan approach or ‘1 step’ approach (see Related ObG Topics below) to both be valid for GDM diagnosis

SYNOPSIS:

GDM is a common complication of pregnancy, possibly affecting 9.2% of all pregnancies (CDC 2010) and appears to be increasing. Aside from well known complications associated with birth trauma and increased risk of operative delivery and preeclampsia, there may be long term complications including increased risk of obesity and diabetes later in life, although maternal obesity and excessive weight gain may be independent risk factors for macrosomia and childhood obesity. Treatment for GDM does appear to improve outcomes. Screening all women is necessary as traditional risk factors may only detect 50% of GDM.

KEY POINTS:

ACOG and consensus panel convened by the NIH do not recommend the ‘one step’ approach, but rather the ‘two step’ approach
- Centers can adopt ‘1 step approach’ if more clinically applicable for a particular population
The ‘one-step’ screening approach will result is increased diagnosis of GDM
The controversy relates to whether with the increased costs and resources necessitated by the ‘one-step’ approach will result in improved outcomes
Targeting obesity and improved nutrition can also address macrosomia risks

Diagnosis code: Gestational diabetes mellitus in pregnancy