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 it is typically managed through a combination of lifestyle modifications and medication when necessary, with insulin being the preferred medication during pregnancy. GDM occurs when the body cannot produce enough insulin to meet the extra needs during pregnancy, resulting in high blood glucose levels. The first-line approach involves dietary changes focusing on controlled carbohydrate intake, regular physical activity (30 minutes of moderate exercise most days), and blood glucose monitoring 4-7 times daily (fasting and 1-2 hours after meals) 1. Target blood glucose levels are typically less than 95 mg/dL fasting and less than 140 mg/dL one hour after meals.
Significance and Relevance to Obstetric Care
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 1. The associations with maternal oral glucose tolerance test (OGTT) results are continuous with no clear inflection points. Offspring with exposure to untreated GDM have reduced insulin sensitivity and β-cell compensation and are more likely to have impaired glucose tolerance in childhood.
Management of GDM
If lifestyle changes don't adequately control blood glucose levels, medication may be needed. Insulin is the preferred medication during pregnancy, with common regimens including NPH insulin (starting at 0.2 units/kg/day) or rapid-acting insulins like lispro or aspart before meals 1. Oral agents like metformin or glyburide may be used in some cases, but they should not be used as first-line agents due to the lack of long-term safety data. GDM requires careful management to prevent complications such as excessive fetal growth, birth injuries, neonatal hypoglycemia, and increased risk of cesarean delivery. 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 follow-up important.
Some key points to consider in the management of GDM include:
- Lifestyle behavior change is an essential component of management of GDM and may suffice as treatment for many individuals 1
- Telehealth visits for pregnant people with GDM improve outcomes compared with standard in-person care 1
- Depending on the population, studies suggest that 70–85% of people diagnosed with GDM under Carpenter-Coustan criteria can manage GDM with lifestyle modification alone 1
- The glycemic goal lower limits defined for preexisting diabetes apply for GDM treated with insulin 1
From the Research
Definition of Gestational Diabetes Mellitus (GDM)
- Gestational diabetes mellitus (GDM) is defined as a state of hyperglycemia that is first recognized during pregnancy 2, 3, 4, 5.
- It is a common condition of pregnancy with increasing prevalence in the United States, affecting approximately 15% of pregnancies worldwide 4.
- GDM is characterized by glucose intolerance resulting in hyperglycemia of variable severity with onset during pregnancy 3.
Significance and Relevance to Obstetric Care
- GDM increases the risk of complications, including operative delivery, hypertensive disorders, shoulder dystocia, fetal macrosomia, large-for-gestational-age infants, neonatal hypoglycemia, and neonatal respiratory distress 2.
- It also increases the risk of long-term complications, including obesity, impaired glucose metabolism, and cardiovascular disease, in both the mother and infant 4, 5.
- The primary treatments for GDM are diet and increased exercise, with insulin, glibenclamide, and metformin used to intensify treatment if necessary 4, 5.
- Effective management of GDM is critical to reduce the risk of adverse pregnancy outcomes and long-term complications 2, 5.
Management of GDM
- First-trimester screening can identify preexisting diabetes and early-onset GDM for prompt implementation of glucose control measures 2.
- Treatment of GDM should start with lifestyle modifications, including dietary changes and increased physical activity 2, 4, 5.
- For patients who are unable to maintain euglycemia with lifestyle modifications alone, insulin is the recommended first-line medication 2.
- Fetal surveillance is suggested starting at 32 weeks of gestation for patients with poor glucose control or who require medications 2.
- The recommended delivery range for patients controlling their glucose levels with lifestyle modifications alone is 39/0 to 40/6 weeks of gestation, and the ideal range for those controlling glucose levels with medications is 39/0 to 39/6 weeks of gestation 2.