There Is No Sugar-Coating Gestational Diabetes

Gestational diabetes (GD) is defined as diabetes that is diagnosed during the second or third trimester of pregnancy. The prevalence of GD is increasing, with the incidence at about 7% of all pregnancies. The etiology of GD is most commonly related to insulin resistance and several placental factors, including human placental lactogen, progesterone, and prolactin, leading to maternal hyperglycemia. Maternal hyperglycemia can cause increased fetal insulin levels and excessive fetal growth, or macrosomia.¹

Risk factors for GD include obesity, previous history of glucose monitoring (GM), and strong family history of type 2 diabetes (T2D). Certain ethnic groups are at increased risk for GD, including African Americans, Asian Americans, Latinos, Native Americans, and Pacific Islanders. Advanced maternal age, excessive early-pregnancy weight gain, and pregnancy with twins are other associated risk factors. Complications of GD include an increased risk of cesarean delivery, preeclampsia, and spontaneous preterm birth. Fetal and neonatal complications include an increased risk of macrosomia, neonatal respiratory problems, shoulder dystocia, and metabolic complications, such as hypoglycemia and polycythemia.²

In addition to antenatal and fetal complications, other long-term consequences exist. Women with GD are more likely to have the condition in subsequent pregnancies. A large population-based, retrospective study demonstrated that women with GD during their first pregnancies have a 41.0% risk of having the condition during their second pregnancies compared with just a 4.2% risk in women without previous GD.³

Women with GD are also at increased risk of developing diabetes, and the risk increases over time. A large population-based study demonstrated that the rate of development of diabetes after GD was almost 19% by 9 years. The risk for T2D was much higher in women with GD who were obese and had a large waist circumference.⁴

Women with GD have a higher risk for cardiovascular disease (CVD) and at a younger age than women without a history of GD. A cross-sectional study concluded that women with GD, especially those with a family history of diabetes, were at a significantly increased risk of coronary artery disease and stroke at a younger age.⁵ Another large longitudinal prospective cohort study followed for 25.7 years demonstrated an elevated risk of myocardial infarction in women, particularly in women with GD that progressed to T2D.⁶

GD is generally asymptomatic, and 90% of pregnant women have at least 1 risk factor for glucose impairment during pregnancy. This supports the rationale for universal GD screening.⁷ Screening for GD is performed for all pregnant women in the United States at between 24 and 28 weeks gestation. The American College of Obstetricians and Gynecologists recommends screening with a 1-hour oral 50-g glucose tolerance test. A 50-g oral glucose load is given, and venous plasma is assessed an hour later. If the 1-hour glucose screening test shows blood glucose levels of 130 mg/ dL, a 3-hour, 100-g glucose tolerance test is ordered to confirm the diagnosis of GD.⁸ GD diagnosis is based on at least 2 diagnostic 3-hour oral glucose thresholds met or exceeded using either of the following criteria:

• Carpenter and Coustan plasma or serum glucose levels 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)
• National Diabetes Data Group plasma glucose levels 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)

After confirming the diagnosis of GD, clinicians should initiate treatment to achieve glycemic control and improve pregnancy outcomes and possibly future health-related outcomes. A combination of exercise, medical nutritional therapy, and blood glucose monitoring is often successful in achieving glycemic goals. When glucose levels are consistently elevated despite nutritional therapy, pharmacologic intervention with either insulin or alternatively glyburide or metformin is indicated. Clinicians should monitor women with GD for recurrence in subsequent pregnancies and the development of T2D. Lifestyle interventions, such as achieving and maintaining a healthy weight, healthy eating, not smoking, and regularly exercising, are beneficial in reducing the risk of diabetes mellitus and related CVDs.⁹

Jennifer L. Hofmann, MS, PA-C, is a clinical associate professor and full-time faculty and pharmacology courses instructor at Pace University-Lenox Hill Hospital PA Program in New York, New York. She is also a PA program adjunct professor for the Touro College School of Health Sciences in Bayshore, New York, and Nassau University Medical Center in East Meadow, New York. In addition, she is a Stony Brook University PA Program postprofessional clinical pharmacology seminar adjunct professor in New YorklCaitlin Henderson, RN, WHNP, practices with an obstetrician-gynecologist in private practice in West Islip, New York.

References

• ACOG Committee on Practice Bulletins. ACOG practice bulletin, Number 60, March 2005. Pregestational diabetes mellitus: Clinical management guidelines for obstetrician-gynecologists. Obstet Gynecol. 2005;105(3):675-685.
• Dodd JM, Crowther CA, Antoniou G, Baghurst P, Robinson JS. Screening for gestational diabetes: the effect of varying blood glucose definitions in the prediction of adverse maternal and infant health outcomes. Aust N Z J Obstet Gynaecol. 2007;47(4):307-312. doi: 10.1111/j.1479-828X.2007.00743.x.
• Getahun D, Fassett MJ, Jacobsen SJ. Gestational diabetes: risk of recurrence in subsequent pregnancies. Am J Obstet Gynecol. 2010;203(5):467.e1-6. doi: 10.1016/ j.ajog.2010.05.032.
• Feig DS, Zinman B, Wang X, Hux JE. Risk of development of diabetes mellitus after diagnosis of gestational diabetes. CMAJ. 2008;179(3):229-234. doi: 10.1503/ cmaj.080012.
• Carr DB, Utzschneider KM, Hull RL, et al. Gestational diabetes mellitus increases the risk of cardiovascular disease in women with a family history of type 2 diabetes. Diabetes Care. 2006;29(9):2078-2083. doi: 10.2337/dc05-2482.
• Tobias DK, Stuart JJ, Li S, et al. Association of history of gestational diabetes with long-term cardiovascular disease risk in a large prospective cohort of US women. JAMA Intern Med. 2017;177(12):1735-1742. doi: 10.1001/jamainternmed.2017.2790.
• Danilenko-Dixon DR, Van Winter JT, Nelson RL, Ogburn PL Jr. Universal versus selective gestational diabetes screening: application of 1997 American Diabetes Association recommendations. Am J Obstet Gynecol. 1999;181(4):798-802.
• Committee on Practice Bulletins—Obstetrics. ACOG practice bulletin No. 190: gestational diabetes mellitus. Obstet Gynecol. 2018;131(2):e49-e64. doi: 10.1097/ AOG.0000000000002501.
• Zhang C, Tobias DK, Chavarro JE, et al. Adherence to healthy lifestyle and risk of gestational diabetes mellitus: prospective cohort study. BMJ. 2014;349:g5450. doi: 10.1136/bmj.g5450.