ACOG and SMFM Both Release Guidance on Gestational Diabetes – Insulin vs Metformin for First-Line Therapy?

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. Compare and contrast the recommendations from ACOG and SMFM regarding the use of insulin or metformin as a preferred therapy for GDM
2. Recall important changes in the 2018 updated ACOG GDM recommendations

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 March 4 2018 through March 3 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.

Designated for 0.2 contact hours of pharmacotherapy credit for Advance Practice Registered Nurses.

Read Disclaimer & Fine Print

SUMMARY:

The SMFM released a statement on the use of metformin as a first-line alternative to insulin in women with GDM. ACOG has also released an update to the major 2017 Practice Bulletin which also addresses this issue and still considers insulin the preferred option to treat women who are not adequately controlled with appropriate nutritional therapy.

Both the ACOG update and SMFM statement summarize the literature, including recent meta-analyses on the comparison studies between insulin and metformin
- Data has been conflicting based on whether non-published studies and women with women with type II diabetes are included
- Some studies have demonstrated a higher risk for preterm birth (but lower for gestational hypertension) in the metformin group while other studies have not identified a difference in preterm birth

ACOG

Based on current evidence, ACOG states that, consistent with ADA guidance, insulin is the ‘preferred’ approach for GDM for women not sufficiently controlled with diet and exercise
In addition, the ACOG update states

Thus, although metformin may be a reasonable alternative approach to treat gestational diabetes, it is important to counsel women about the lack of superiority when compared with insulin, the placental transfer of the drug, and the absence of long-term data in exposed offspring. Additionally, in the aforementioned prospective trials, between 26% and 46% of women who took metformin alone eventually required insulin.

SMFM

Upon review of the evidence, SMFM considers metformin to be a “reasonable and safe first-line pharmacologic alternative to insulin”
More data is needed to establish long-term safety of oral agents
Glyburide has been associated with adverse neonatal events, such as macrosomia and hypoglycemia but SMFM also acknowledges that “the evidence of benefit of one oral agent over the other remains limited”
SMFM does acknowledge that their statement conflicts with ACOG, however

…this difference is based on the values placed by different experts and providers on the evidence available in the medical literature and is not meant to represent an exclusive course of management.

KEY POINTS:

Other ACOG Updates

One abnormal values on the 3 hour OGTT

In the previous 2017 practice bulletin, while it was clearly stated that diagnosis of GDM is based on 2 abnormal values on the 3 hour OGTT, ACOG seemed to suggest that one abnormal value may be sufficient to make the diagnosis
In the updated 2018 version, ACOG has clarified that statement
- One abnormal glucose level may warrant a higher level of scrutiny, but is not sufficient for diagnosis
- More studies are required to determine risk of adverse outcomes and who would benefit from making this a diagnostic criteria

Clarification of insulin use and dosage

ACOG has clarified the previous practice bulletin and now states that in women who have abnormal postprandial and fasting glucose levels
- Insulin starting dose is 0.7-1.0 units/kg daily
- Dosage should be divided and long-acting or intermediate-acting insulin in combination with short-acting insulin should be used
Previously, the 2017 documented stated that insulin was ‘first line’ therapy and the updated document now says ‘preferred’
- ACOG recognizes that clinicians may assess the clinical circumstances and find the use of oral agents to be a better alternative in women (e.g., patient cannot afford insulin or feel administering the drug would be unsafe)

Macrosomia and cesarean section

The recommendation that women with GDM should be counseled about the risks/benefits of a scheduled cesarean section if the estimated fetal weight is ≥4,500 g has been moved from ‘limited or inconsistent scientific evidence’ (Level B) to ‘consensus and expert opinion’ (Level C)