What is gestational diabetes mellitus (GDM) and how is it managed?

From the Guidelines

Gestational diabetes mellitus (GDM) is a type of diabetes that develops during pregnancy in women who didn't have diabetes before becoming pregnant, and its management should prioritize lifestyle modifications and insulin therapy as the first-line treatment, as recommended by the most recent guidelines 1. GDM typically develops in the second or third trimester and affects approximately 2-10% of pregnancies.

Key Characteristics of GDM

• It occurs when the body cannot produce enough insulin to meet the extra needs during pregnancy, resulting in high blood glucose levels.
• GDM is characterized by an increased risk of large-for-gestational-age birth weight and neonatal and pregnancy complications, as well as an increased risk of long-term maternal type 2 diabetes and abnormal glucose metabolism in offspring in childhood, as noted in recent studies 1.

Management of GDM

• Management begins with lifestyle modifications including a balanced diet low in simple carbohydrates, regular moderate exercise (30 minutes daily), and blood glucose monitoring 4-7 times daily.
• Target blood glucose levels are typically below 95 mg/dL fasting and below 140 mg/dL one hour after meals.
• If lifestyle changes are insufficient, medication may be necessary, with insulin being the preferred medication for treating hyperglycemia in GDM, as it does not cross the placenta to a measurable extent 1.
• Oral agents such as metformin may be used in some cases, but their use should be carefully considered due to the lack of long-term safety data 1.

Significance and Relevance to Obstetric Care

• GDM requires close monitoring with regular prenatal visits every 1-2 weeks and ultrasounds to assess fetal growth.
• Most women with GDM return to normal blood glucose levels after delivery, but they have an increased risk of developing type 2 diabetes later in life, making postpartum screening at 6-12 weeks essential, as emphasized in recent guidelines 1.
• The use of telehealth visits for pregnant people with GDM has been shown to improve outcomes compared with standard in-person care, as demonstrated in a meta-analysis of 32 RCTs 1. Some key points to consider in the management of GDM include:
• The importance of early diagnosis and treatment to reduce the risk of complications.
• The need for close monitoring and regular prenatal visits to assess fetal growth and maternal health.
• The potential benefits of telehealth visits in improving outcomes for women with GDM.
• The importance of postpartum screening for type 2 diabetes in women who have had GDM, as recommended by recent guidelines 1.

From the Research

Definition of Gestational Diabetes Mellitus (GDM)

• Gestational diabetes mellitus (GDM) is defined as any degree of glucose intolerance with onset or first recognition during pregnancy 2.
• It is a common condition of pregnancy with increasing prevalence in the United States 3.
• GDM is associated with adverse pregnancy outcomes and long-term offspring and maternal complications 2.

Significance and Relevance to Obstetric Care

• GDM increases risks of complications, including operative delivery, hypertensive disorders, shoulder dystocia, fetal macrosomia, large-for-gestational-age infants, neonatal hypoglycemia, and neonatal respiratory distress 3.
• Maternal overweight and obesity, later age at childbearing, previous history of GDM, family history of type 2 diabetes mellitus, and ethnicity are major GDM risk factors 4.
• Treatment of GDM has been shown to reduce the risk of complications and should start with lifestyle modifications, including dietary modification and increased physical activity 3, 4.
• For patients who are unable to maintain euglycemia with lifestyle modifications alone, insulin is the recommended first-line medication 3.
• GDM increases the risk of long-term complications, including obesity, impaired glucose metabolism, and cardiovascular disease, in both the mother and infant 4, 2.

Management of GDM

• First-trimester screening can identify preexisting diabetes and early-onset GDM for prompt implementation of glucose control measures 3.
• A two-step approach (1-hour 50 g glucose challenge test followed by 3-hour 100 g oral glucose tolerance test) or a one-step approach (75 g oral glucose tolerance test) can be used for GDM screening and diagnosis 2.
• Dietary interventions, such as the Dietary Approaches to Stop Hypertension (DASH) diet and low-glycemic index (Low-GI) diet, have been shown to be effective in managing GDM 5.
• Early screening and treatment of GDM, including early gestational diabetes mellitus (eGDM), can improve pregnancy outcomes and reduce the risk of complications 6.