In the United States, screening for
gestational diabetes generally has been
performed using a two-step approach:
an initial 50-gram glucose challenge test,
which is followed by a 100-gram oral
glucose tolerance test for those who have
an initial abnormal screen. This approach
was recently investigated in a randomized
clinical trial in the United States, and
the results suggest that screening and
treating those diagnosed with gestational
diabetes reduces the risk of some perinatal
complications, including macrosomia
and shoulder dystocia.
Recently, another group of investigators
tested a one-step screening and diagnostic
strategy in which patients were screened
and diagnosed based on a one-time,
two-hour, 75-gram glucose tolerance test.
The main advantage of this strategy is
that it requires a single test, which likely
would increase patient satisfaction and
would be less expensive in the short-term
than the two-step approach. In December
2010, the American Diabetes Association
(ADA) recommended that providers in
the United States use the one-step test.
This recommendation has led to
confusion and controversy among
providers of obstetrical care.
The Committee on Obstetric Practice of
the American College of Obstetricians and
Gynecologists (ACOG) issued an opinion
in August 2011 about the best strategy
for gestational diabetes screening. Simply
put, ACOG recommends that at this time
the two-step process should remain the
standard in the United States.
The reasons for this are two-fold. First,
due to false positives, the one-step, 75-
gram test would lead to diagnoses of
gestational diabetes in approximately 18
percent of subjects, compared to roughly
5 percent when using the two-step test.
This high rate of “diagnosis” could lead to
many unnecessary tests and interventions.
Second, the one-step strategy has not been
as well tested as the two-step strategy. For
both of these reasons, according to ACOG,
practitioners should use the two-step
approach for screening and diagnosis of
We can expect to receive additional
information on this issue soon. The Agency
for Healthcare Quality and Research is
developing an evidence-based document
on screening for gestational diabetes. In
addition, the National Institutes of Health
(NIH) will hold a Consensus Conference
on this issue in October 2012.