Gestational Diabetes Mellitus: Definition and Impact on Short- and Long-Term Outcomes in Mothers and Offspring

Instituto Nacional de Perinatología Isidro
Espinosa de los Reyes, Mexico City, Mexico
rod.zamora@gmail.com

Department of Endocrinology,
Instituto Nacional de Perinatología Isidro
Espinosa de los Reyes, Mexico City, Mexico

• Considering the increasing number of women at risk of GDM (e.g. of those who are overweight or obese), it is necessary to identify those at risk and perform screening and diagnostic tests from the first prenatal visit.
• Diagnosing and treating GDM is very important in order to reduce serious adverse pregnancy outcomes, neonatal complications, the number of cesarean sections, and an increased maternal and offspring predisposition to T2DM later in life.

For many years, gestational diabetes mellitus (GDM) has been defined as any degree of glucose intolerance first diagnosed during pregnancy, regardless whether this condition has already existed before the pregnancy or whether it will persist after it. This definition has resulted in a uniform system for the detection and classification of GDM and for treatment strategies, but this system is limited because of its imprecision [1].

The current, global, and growing prevalence of obesity and type 2 diabetes mellitus (T2DM) means that an increasing number of women of childbearing age are overweight or obese and that a rising number of pregnant women present with undiagnosed T2DM. It is therefore necessary to perform screening or diagnostic tests in women at risk of T2DM, from the first prenatal visit, using standard diagnostic criteria for the general population. Women diagnosed with abnormal glucose levels during the first trimester of pregnancy should be classified as carriers of pregestational T2DM, while those diagnosed during the second or third trimester should be classified as GDM cases using the current definition [2, 3].

It is important to diagnose and treat GDM because of its association with adverse pregnancy outcomes. Macrosomia, shoulder dystocia, and neonatal hypoglycemia are frequently occurring serious complications. In patients with GDM, a greater number of cesarean sections and an increased risk of preeclampsia are common. Jaundice, polycythemia, respiratory failure, and hypocalcemia have also been reported as frequent neonatal complications, and increased perinatal mortality. Fetal exposure to hyperglycemia can predispose the child to T2DM later in life [4–6].

Currently, T2DM is the leading cause of death among Mexican women, and obesity is a major risk factor for developing T2DM. In Mexico, it has been estimated that 69% of all women of childbearing age are overweight or obese, and the number of pregnant women with GDM is increasing, with an estimated prevalence between 8 and 12%. These figures should be enough reason for screening of GDM and diagnostic strategies to be performed in all pregnant women in countries with similar percentages, but unfortunately this is not generally the case.

Additionally, a history of GDM puts the mother at an increased risk of recurrence during further pregnancies and of developing T2DM, as well as potentially of cardiovascular disease. Hyperglycemia in GDM is usually mild and of a too short duration to adversely affect a woman’s health. However, an affected woman’s long-term risk of developing overt T2DM is high, ranging between 2.6 and 70% in follow-up studies between 6 weeks and 28 years after delivery [7]. At least one third of all women with GDM show recurrence in a subsequent pregnancy. These risks can be minimized by good glycemic control and adequate obstetric care.

1. American Diabetes Association: Section 2: Classification and diagnosis of diabetes. In: Standards of Medical Care in Diabetes – 2016. Diabetes Care 2016;39:S13–S22.
2. Metzger BE, Gabbe SG, Persson B, et al; International Association of Diabetes and Pregnancy Study Groups Consensus Panel: International Association of Diabetes and Pregnancy Study Groups recommendations on the diagnosis and classification of hyperglycemia in pregnancy. Diabetes Care 2010;33:676–682.
3. Metzger BE, Lowe LP, Dyer AR, et al; HAPO Study Cooperative Research Group: Hyperglycemia and adverse pregnancy outcomes. N Engl J Med 2008;358:1991–2002.
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6. Vandorsten JP, Dodson WC, Espeland MA, et al: NIH consensus development conference: diagnosing gestational diabetes mellitus. NIH Consens State Sci Statements 2013;29:1–31.
7. Kim C, Newton KM, Knopp RH: Gestational diabetes and the incidence of type 2 diabetes: a systematic review. Diabetes Care 2002;25:1862–1868.