Obstetrics & Gynecology, also known as The Green Journal, is a leading medical journal and one of the most influential publications guiding the practice of obstetrics and gynecology in the United States. In November 2024, the Green Journal devoted an entire special issue to diabetes in pregnancy, reflecting the importance of this topic in current obstetric practice. The special issue included research on:

• Factors creating challenges for managing diabetes during pregnancy
• strategies to improve diabetes management during pregnancy, with particular focus on the use of Continuous Glucose Monitors (CGMs).
• Insulin and metformin as treatment options for diabetes during pregnancy

As a general OB-Gyn physician who regularly cares for pregnant patients with diabetes, I found this special issue highly informative. In this article, I’ve collected some of the most impactful statistics and key insights to help fellow OB-Gyns get up to speed on the cutting edge of gestational diabetes research today.

Roughly 1 in 6 live births are affected by gestational or type 2 diabetes.³

New Statistics Illustrating the Scope of the Problem

The special issue presents several statistics highlighting the widespread nature of diabetes:

• About 5% (1 in 20) of Americans aged 18-44 are affected by diabetes.²
• Diabetes has emerged as the most common metabolic disorder during pregnancy, with roughly 1 in 6 live births affected, primarily by gestational or type 2 diabetes.³
• With the rapid rise in childhood and adolescent diabetes, the prevalence of diabetes during pregnancy is expected to continue growing.⁴

These statistics underscore the importance of prioritizing diabetes in pregnancy as a key area for current and future research.

Risks for Pregnancies Complicated by Diabetes 

Diabetes during pregnancy can have serious health implications for mothers and babies. Before insulin became available, maternal and perinatal mortality (mothers and/or babies dying during pregnancy or shortly thereafter) was as high as 50%.⁵

While considerable advances have been made in managing diabetes during pregnancy, the condition still presents serious health risks. Many of the journal articles mention "poor maternal and perinatal outcomes" in general terms, but it is essential to highlight the specific risks in more detail.

Pregnancy-related risks related to any type of diabetes during pregnancy

• Hypertensive disorders of pregnancy, including preeclampsia
• Abnormal fetal growth and/or amniotic fluid levels, increasing the risk of preterm birth and associated complications for premature infants
• Excessive fetal growth, which may lead to delivery complications and birth trauma
• All these factors contribute to a higher likelihood of requiring a cesarean delivery

Preexisting diabetes increases the likelihood
of stillbirth and perinatal mortality by 3x.⁶

Pregnancy-related risks that are higher with pregestational diabetes (preexisting Type 1 or Type 2 diabetes)

• For those with poor prepregnancy glucose control, there is an increased risk of fetal congenital anomalies (such as heart and spine defects).
• Stillbirth. A systematic review and meta-analysis in this issue found that preexisting diabetes increases the likelihood of stillbirth and perinatal mortality by three-fold, with a stronger association observed for type 2 diabetes compared to type 1 diabetes.⁶
• Diabetic ketoacidosis. Although diabetic ketoacidosis (DKA) is primarily associated with type 1 diabetes, it can also occur in individuals with type 2 diabetes. A cross-sectional study examining trends in the United States found that the prevalence of DKA during pregnancy has more than doubled from 0.7% to 2.0% between 2010 and 2020.⁷

Ongoing risks after delivery

For babies:

• Difficulty regulating blood sugar after birth, often necessitating a NICU stay.
• Increased risk of developing diabetes in childhood and later in life.

For mothers:

• Increased risk of developing type 2 diabetes following gestational diabetes.
• Those with preexisting diabetes have an increased risk of permanent damage to critical organs such as the kidneys, heart, and eyes.

Challenges in Diabetes Management during Pregnancy

Managing diabetes during pregnancy presents several challenges, particularly when it comes to access to care. Healthcare deserts—whether geographic or socioeconomic—can limit access to essential services, leading to undiagnosed pregestational diabetes due to inadequate prepregnancy care. During pregnancy, diabetes management requires more frequent interactions with the healthcare system for blood glucose monitoring, fetal monitoring, and regular visits to healthcare providers. Unfortunately, the shortage of healthcare providers often fails to meet the needs of this population, leading to serious consequences. As noted earlier, the absence of prenatal or prepregnancy diabetes care significantly increases the risk of stillbirth and perinatal mortality.⁸

Socioeconomic factors also play a major role in diabetes management. Limited access to education, diabetes equipment, and healthy foods—especially in areas with food insecurity—can worsen outcomes. A study examining neighborhood socioeconomic factors found that pregnant individuals in more deprived areas were at a higher risk of developing gestational diabetes compared to those in less deprived neighborhoods. Notably, prepregnancy BMI accounted for nearly half (46%) of this association, which was also linked to poorer cardiometabolic health.⁹

Approaches to Improve Diabetes Care during Pregnancy

Many of the poor outcomes associated with diabetes during pregnancy are believed to be preventable through improved care for women and children before, during, and after pregnancy. This journal issue focuses primarily on strategies to improve management during pregnancy. Pregnancy presents a unique challenge in glucose management, as the constant hormonal changes required to support the fetus can directly affect the mother's ability to control blood sugar levels.

Technology in Diabetes Management

Technological advances in diabetes management for the general population have been slow to reach pregnant individuals. Devices like continuous glucose monitors (CGMs) and insulin pumps, which have primarily been studied in individuals with type 1 diabetes, could also benefit those with type 2 diabetes and gestational diabetes, who make up the majority of diabetes cases in pregnancy.¹⁰ The previously referenced study on stillbirth and perinatal mortality related to preexisting diabetes concluded that future studies should explore whether CGM metrics such as time in range and glycemic variability can better predict severe adverse pregnancy outcomes.¹¹ CGMs were a popular topic of several articles in this special issue and will be discussed in more detail in the next section.

Another advantage of these new technologies is that they enable remote monitoring, which can help overcome access-to-care challenges, including provider shortages and geographic barriers.

Group Prenatal Care

A systematic review by Carter EB et al¹² comparing group prenatal care with individual care for patients with type 2 diabetes or gestational diabetes found no significant differences in outcomes including preterm birth, large-for-gestational-age (LGA) infants, small-for-gestational-age (SGA) infants, cesarean delivery, neonatal hypoglycemia, and NICU admission. However, group prenatal care was associated with better uptake of long-acting reversible contraception (LARC) methods and higher rates of postpartum 2-hour glucose tolerance test (GTT) completion. Given that group prenatal care appears to offer comparable, if not better, outcomes than individual care, it may serve as an effective solution to improve access to care.

Every Other Day Glucose Monitoring

A randomized trial by Feldman KM et al¹³ (p. 707) examining glucose monitoring frequency in patients with GDM found that every other day testing was as effective as daily testing, without negatively affecting birth weight, medication initiation, or glucose control. This approach could reduce the emotional, physical, and financial burdens on patients with GDM by offering a less intrusive alternative.

Special Focus on Continuous Glucose Monitoring (CGM)

Multiple articles focus specifically on the use of continuous glucose monitoring (CGM) for managing diabetes during pregnancy. CGMs are wearable devices that continuously measure glucose levels in the interstitial fluid, offering several potential benefits. They can transmit data via Bluetooth, enabling more convenient and reliable data collection. CGMs provide more comprehensive data compared to the traditional method of checking blood glucose with fingersticks (typically 4-7 times a day), allowing for better detection of glucose trends and enabling real-time corrections. They also have the potential to be used as a screening tool for diabetes (as an alternative to Hemoglobin A1c or glucose tolerance tests).¹⁴

Despite some advantages to CGM use, there are also some challenges. One limitation of CGMs is that the interstitial glucose values they measure may lag behind capillary blood glucose levels by 10-15 minutes. This can introduce some potential inaccuracies in the readings. Additionally, patients may experience anxiety, skin irritation, and/or alarm fatigue, which could limit the effectiveness of the device.¹⁵

Pregnant patients with Type 2 diabetes
using CGMs had 70% fewer NICU admissions.¹⁷

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I’d like to highlight two original research articles related to CGMs included in this issue.

• One prospective observation study by Durnwald C et al¹⁶ looked at any CGM patterns associated with adverse pregnancy outcomes and found that patients with large for gestational age neonates or hypertensive disorders of pregnancy had higher mean glucose levels and spent more time above 120 and 140, regardless of whether they had a gestational diabetes diagnosis. This suggests that CGMs may be useful in identifying individuals at higher risk of adverse perinatal outcomes associated with abnormal glucose levels.
• A second retrospective cohort study by Padgett CE et al¹⁷ found that pregnant patients with Type 2 diabetes using CGMs had 50% less neonatal morbidity and preterm birth and 70% fewer NICU admissions.

Both studies concluded that while CGM use for diabetes in pregnancy is promising, further research (including randomized controlled trials) is needed to evaluate the effectiveness of CGMs in type 2 diabetes and gestational diabetes.

Insulin and Metformin as Treatment Options for Diabetes During Pregnancy

Insulin and metformin are the most commonly prescribed medications for managing diabetes during pregnancy. Insulin, which does not cross the placenta, is still considered the standard of care. The November journal issue features a useful Clinical Expert Series by Valent AM and Barbour LA¹⁸ providing clinicians with updated guidance on how to personalize insulin types and technologies to manage gestational and type 2 diabetes during pregnancy.

A separate Narrative Review article by Newman C and Dunne FP¹⁹ examines the evidence supporting the use of metformin, highlighting its benefits and potential drawbacks. While metformin is considered a safe alternative to insulin, it does cross the placenta, raising concerns about its potential effects on the fetus. Some studies have linked metformin use during pregnancy to higher obesity rates in children. The authors emphasize the need for further research to better understand the long-term outcomes for children born to mothers who used metformin during pregnancy.

Looking Ahead to the Future of Diabetes in Pregnancy

While substantial progress has been made in improving outcomes for women with diabetes during pregnancy, much work still lies ahead. The special November 2024 issue of Obstetrics & Gynecology presents some promising strategies and technologies that may lead to better maternal and perinatal outcomes while also improving cost-effectiveness and convenience for patients. Ongoing research and focus on this critical issue are essential!

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References:

1. Obstetrics & Gynecology. Obstet Gynecol. 2024;144(5).
2. Smith J, Johnson M, Lee T. Integrated strategies to support diabetes technology in pregnancy. Obstet Gynecol. 2024;144(5):599-607.
3. Egan AM, Werner EF. Forward. Obstet Gynecol. 2024;144(5):575.
4. Smith J, Johnson M, Lee T. Integrated strategies to support diabetes technology in pregnancy. Obstet Gynecol. 2024;144(5):599-607.
5. Egan AM, Werner EF. Forward. Obstet Gynecol. 2024;144(5):575.
6. Blankstein AR, Sigurdson SM, Frehlich L, et al. Pre-existing diabetes and stillbirth or perinatal mortality. Obstet Gynecol. 2024;144(5):608-19.
7. Wen T, Friedman AM, Gyamfi-Bannerman C, et al. Diabetic Ketoacidosis and Adverse Outcomes Among Pregnant Individuals With Pregestational Diabetes in the United States, 2010-2020. Obstet Gynecol. 2024;144(5):579-89.
8. Blankstein AR, Sigurdson SM, Frehlich L, et al. Pre-existing diabetes and stillbirth or perinatal mortality. Obstet Gynecol. 2024;144(5):608-19.
9. Liu EF, Ferrara A, Sridhar SB, Greenberg MB, Hedderson MM. Association Between Neighborhood Deprivation in Early Pregnancy and Gestational Diabetes Mellitus. Obstet Gynecol. 2024;144(5):670-76.
10. Nally LM, Blanchette JE. Integrated Strategies to Support Diabetes Technology in Pregnancy. Obstet Gynecol. 2024;144(5):599-607.
11. Blankstein AR, Sigurdson SM, Frehlich L, et al. Pre-existing diabetes and stillbirth or perinatal mortality. Obstet Gynecol. 2024;144(5):608-19.
12. Carter EB, Thayer SM, Paul R, et al. Diabetes Group Prenatal Care: A Systematic Review and Meta-analysis. Obstet Gynecol. 2024;144(5):621-32.
13. Feldman KM, Coughlin A, Feliciano J, et al. Neonatal Birth Weight With Daily Compared With Every-Other-Day Glucose Monitoring in Gestational Diabetes Mellitus. Obstet Gynecol. 2024;144(5):707-14.
14. Nally LM, Blanchette JE. Integrated Strategies to Support Diabetes Technology in Pregnancy. Obstet Gynecol. 2024;144(5):599-607.
15. Padgett CE, Ye Y, Champion ML, et al. Continuous Glucose Monitoring for Management of Type 2 Diabetes and Perinatal Outcomes. Obstet Gynecol. 2024;144(5):677-83.
16. Durnwald C, Beck RW, Li Z, et al. Continuous Glucose Monitoring-Derived Differences in Pregnancies With and Without Adverse Perinatal Outcomes. Obstet Gynecol. 2024;144(5):684-96.
17. Padgett CE, Ye Y, Champion ML, et al. Continuous Glucose Monitoring for Management of Type 2 Diabetes and Perinatal Outcomes. Obstet Gynecol. 2024;144(5):677-83.
18. Valent AM, Barbour LA. Insulin Management for Gestational and Type 2 Diabetes in Pregnancy. Obstet Gynecol. 2024;144(5):633-47.
19. Newman C, Dunne FP. Treatment of Diabetes in Pregnancy with Metformin. Obstet Gynecol. 2024;144(5):660-69.

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