Applied Evidence

Gestational diabetes: Optimizing Dx and management in primary care

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Understanding risk factors and glucose targets for gestational diabetes can help you identify at-risk patients and improve outcomes for mother and infant.


› 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



Gestational diabetes mellitus (GDM), defined as new-onset hyperglycemia detected in a pregnant woman after 24 weeks of gestation, affects 4% to 10% of pregnancies in the United States annually1 and is a major challenge for health care professionals.2 During pregnancy, the body’s physiologic responses are altered to support the growing fetus. One of these changes is an increase in insulin resistance, which suggests that pregnancy alone increases the patient’s risk for type 2 diabetes (T2D). However, several other factors also increase this risk, including maternal age, social barriers to care, obesity, poor weight control, and family history.

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If not controlled, GDM results in poor health outcomes for the mother, such as preeclampsia, preterm labor, and maternal T2D.3-5 For the infant, intrauterine exposure to persistent hyperglycemia is correlated with neonatal macrosomia, hypoglycemia, perinatal complications (eg, preterm delivery, fetal demise), and obesity and insulin resistance later in life.4

Primary care physicians (PCPs) are the patient’s main point of contact prior to pregnancy. This relationship makes PCPs a resource for the patient and specialists during and after pregnancy. In this article, we discuss risk factors and how to screen for GDM, provide an update on practice recommendations for treatment and management of GDM in primary care, and describe the effects of uncontrolled GDM.

Know the key risk factors

Prevention begins with identifying the major risk factors that contribute to the development of GDM. These include maternal age, social barriers to care, family history of prediabetes, and obesity and poor weight control.

Older age. A meta-analysis of 24 studies noted strong positive correlation between GDM risk and maternal age.6 One of the population-based cohort studies in the meta-analysis examined relationships between maternal age and pregnancy outcomes in women living in British Columbia, Canada (n = 203,414). Data suggested that the relative risk of GDM increased linearly with maternal age to 3.2, 4.2, and 4.4 among women ages ≥ 35, ≥ 40, and ≥ 45 years, respectively.7

Social barriers to care. Although the prevalence of GDM has increased over the past few decades,1 from 2011 to 2019 the increase in GDM in individuals at first live birth was significantly higher in non-Hispanic Asian and Hispanic/Latina women than in non-Hispanic White women.8 Data from the Centers for Disease Control and Prevention further suggest that diabetes was more prevalent among individuals with a lower socioeconomic status as indicated by their level of education.9 Ogunwole et al10 suggest that racism is the root cause of these disparities and leads to long-term barriers to care (eg, socioeconomic deprivation, lack of health insurance, limited access to care, and poor health literacy), which ultimately contribute to the development of GDM and progression of diabetes. It is important for PCPs and all health professionals to be aware of these barriers so that they may practice mindfulness and deliver culturally sensitive care to patients from marginalized communities.

Family history of prediabetes. In a population-based cohort study (n = 7020), women with prediabetes (A1C, 5.7%-6.4%) were 2.8 times more likely to develop GDM compared with women with normal A1C (< 5.7%).11 Similar results were seen in a retrospective cohort study (n = 2812), in which women with prediabetes were more likely than women with a normal first trimester A1C to have GDM (29.1% vs 13.7%, respectively; adjusted relative risk = 1.48; 95% CI, 1.15-1.89).12 In both studies, prediabetes was not associated with a higher risk for adverse maternal or neonatal outcomes.11,12

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