The argument against the one-step approach has been that it increases the incidence of GDM significantly, without proven improvement in maternal and/or perinatal outcomes
Our meta-analysis of RCTs, however, provides level-1 evidence that the one-step approach significantly improves perinatal outcomes
In particular, we found a 54% reduction in the risk of LGA
Screening for gestational diabetes mellitus: one step versus two step approach. A meta-analysis of randomized trials
Professional organizations agree that all pregnant women should be screening for Gestational Diabetes Mellitus (GDM). While there are varying approaches, ACOG and a consensus panel convened by the NIH have endorsed the following ‘2 step’ approach to screening for GDM:
STEP 1: All women should be screened for GDM between 24 and 28 weeks gestation with a 50g oral glucose solution followed by a 1 hour venous glucose measurement. Healthcare providers have the option of using the following values:
Patient is overweight with BMI of 25 (23 in Asian Americans) and one of the following:
If a patient with risk factors is tested earlier and is screen negative, the patient should still be screened again between 24-28 weeks using the 50g oral glucose load.
STEP 2: If screen positive following STEP 1, a diagnostic test, the 100g 3 hour oral glucose tolerance test (OGTT), is recommended. A diagnosis is made if at least two values are exceeded using one of two methods:
Note: ACOG recommends that currently there is insufficient evidence to diagnose GDM based on only one abnormal value | Patients with only one elevated value may require additional surveillance
National Diabetes Data Group
Carpenter and Coustan
GDM is a common complication of pregnancy. Aside from well-known complications associated with birth trauma and increased risk of operative delivery and preeclampsia, there may be long term complications including increased risk of obesity and diabetes later in life, although maternal obesity and excessive weight gain may be independent risk factors for macrosomia and childhood obesity. Treatment for GDM does appear to improve outcomes. Screening all women is necessary as traditional risk factors may only detect 50% of GDM.
ACOG Practice Bulletin No. 190: Gestational Diabetes Mellitus
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