Gestational diabetes: Optimizing Dx and management in primary care
Understanding risk factors and glucose targets for gestational diabetes can help you identify at-risk patients and improve outcomes for mother and infant.
PRACTICE RECOMMENDATIONS
› Manage gestational diabetes mellitus (GDM) with lifestyle behavior changes first and add insulin as a secondary treatment only if glycemic targets are not being met. A
› Treat hyperglycemia in GDM with insulin, not metformin or glyburide; these agents cross the placenta to the fetus. A
Strength of recommendation (SOR)
A Good-quality patient-oriented evidence
B Inconsistent or limited-quality patient-oriented evidence
C Consensus, usual practice, opinion, disease-oriented evidence, case series
Ultimately, earlier intervention—prior to conception—helps patients prepare for a healthier pregnancy, resulting in better long-term outcomes. It is helpful to be familiar with the advantages and disadvantages of common approaches to weight management and to be able to refer patients to nutritionists for optimal planning. When establishing a dietary plan, consider patient-specific factors, such as cultural diets, financial and time constraints, and the patient’s readiness to make and maintain these changes. Consistent follow-up and behavioral therapy are necessary to maintain successful weight control.
There are many screening tools, but 1 is preferred in pregnancy
There are several ways to diagnose diabetes in patients who are not pregnant, including A1C, a fasting glucose test, an oral glucose tolerance test (OGTT), or random glucose testing (plus symptoms). However, the preferred method for diagnosing GDM is OGTT because it has a higher sensitivity.20 A1C, while a good measure of hyperglycemic stability, does not register hyperglycemia early enough to diagnose GDM and fasting glucose testing is less sensitive because for most women with GDM, that abnormal postprandial glucose level is the first glycemic abnormality.21
When to screen. Blood glucose levels should be checked in all pregnant women as part of their metabolic panel at the first prenatal visit. A reflex A1C for high glucose levels can be ordered based on the physician’s preference. This may help you to identify patients with prediabetes who are at risk for GDM and implement early behavioral and lifestyle changes. However, further research is needed to determine if intervention early in pregnancy can truly reduce the risk of GDM.11
Screening for GDM should be completed at 24 to 28 weeks of gestation20 because it is likely that this is when the hormonal effects of the placenta that contribute to insulin resistance set the woman up for postprandial hyperglycemia. Currently, there are no evidence-based guidelines for the use of continuous glucose monitoring prior to 24 weeks of gestation to identify GDM.20 If persistent hyperglycemia is present before 24 weeks of gestation, it is considered evidence of a pre-existing metabolic abnormality and is diagnosed as “pregestational diabetes.” Treatment should follow guidelines established for women who had diabetes prior to pregnancy.
How to screen? There is ongoing discussion about what is the optimal screening method for GDM: a 1-step strategy with a fasting 75-g OGTT only, or a 2-step strategy with a 50-g non-fasting glucose load test followed by a fasting 100-g OGTT in women who do not meet the plasma glucose cutoff (TABLE 1).22-24 Hillier et al25 compared the effectiveness of these strategies in diagnosing GDM and identifying pregnancy complications for the mother and infant. They found that while the 1-step strategy resulted in a 2-fold increase in the diagnosis of GDM, it did not lead to better outcomes for mothers and infants when compared with the 2-step method.25 Currently, the majority of obstetricians (95%) prefer to use the 2-step method.24
Continue to: Manage lifestyle, monitor glucose
