Perinatal outcomes after adopting 1- versus 2-step approach to diagnosing gestational diabetes

The American College of Obstetricians and Gynecologists (ACOG) and the IADPSG (International Association of Diabetes and Pregnancy Study Groups) proposed distinct approaches to diagnosing gestational diabetes mellitus (GDM). We sought to analyze these paradigms: (1) ACOG 2-step approach where screening is followed by diagnostic testing, (2) IADPSG 1-step diagnostic testing.

We reviewed data from pregnant women (24-28 wks) screened for GDM over two periods: (1) November 2011-May 2012 (2) November 2012-May 2013. Period 1: 2-step approach (screening 1-h glucose challenge test (GCT) followed by a diagnostic 3-h 100-g glucose tolerance test (GTT) when abnormal (≥140 mg/dl)). Period 2: an abnormal value after a 2-h 75-g GTT result was diagnostic of GDM. We compared the incidence of GDM and perinatal outcomes using either approach.

Out of 471 patients screened by ACOG 2-step approach, 72 (15.3%) had an abnormal 1-h screening and underwent the 3-h diagnostic GTT, and 26 (5.5%) developed GDM. The 1-step approach resulted in 53 (15.96%) with GDM of a total 332 evaluated. There was no statistically significant difference in perinatal outcomes between the two cohorts. Maternal weight at the start and the end of pregnancy was greater for patients diagnosed by the ACOG 2-step approach.

Adopting 1-step approach (ADA) to diagnose GDM resulted in a 3-fold increase in prevalence of GDM with no differences in perinatal outcomes.