Screening and diagnosing gestational diabetes mellitus

Area of Science:

• Obstetrics and Gynecology
• Endocrinology
• Public Health

Background:

• Uncertainty exists regarding the optimal approach for screening and diagnosing gestational diabetes mellitus (GDM).
• Previous systematic reviews found insufficient evidence to recommend routine GDM screening for all pregnant women.

Purpose of the Study:

• Identify properties of GDM screening tests.
• Evaluate the benefits and harms of GDM screening.
• Assess the impact of different screening and diagnostic thresholds on maternal and infant outcomes.
• Determine the benefits and harms of GDM treatment.

Main Methods:

• Systematic review of 15 electronic databases (1995-2012), gray literature, and trial registries.
• Included randomized controlled trials, nonrandomized controlled trials, and cohort studies.
• Analyzed outcomes such as preeclampsia, birth injury, macrosomia, and long-term metabolic health.

Main Results:

• Prevalence of GDM varied significantly across diagnostic criteria.
• The 50g oral glucose challenge test shows high negative predictive value but variable positive predictive value.
• Treatment for GDM demonstrated moderate evidence for reducing preeclampsia and macrosomia, with insufficient evidence for other outcomes.
• Limited evidence suggests increased prenatal visits as a potential harm of GDM treatment.

Conclusions:

• Evidence supports a link between elevated glucose levels and macrosomia/cesarean sections, but clear risk thresholds are lacking.
• GDM treatment effectively reduces preeclampsia and macrosomia.
• Current evidence does not confirm treatment effects on neonatal hypoglycemia or long-term metabolic outcomes.
• Further research is needed on long-term offspring outcomes and real-world impacts of GDM treatment.