50gram oral glucose challenge test combined with risk factor-based screening for gestational diabetes

Abstract

Objective: Our aim was to study whether universal screening of all pregnant women by Oral Glucose Challenge Test (OGCT) would identify a higher number of women with Gestational Diabetes (GDM) than risk factor based screening.

Study design: A 50 g OGCT test was performed prospectively in 532 unselected women at 26-28 weeks of gestation. The 1-h venous plasma glucose concentration of >7.3 mmol/l was considered as a positive screening result. Patients with a positive OGCT underwent a 75 g 2-h OGTT, which was used as the actual diagnostic test for GDM. When two or all three of the glucose concentrations in OGTT (measured at fasting state and 1 and 2 h after the 75 g glucose load) were above the 97.5th percentile the patient was considered as having GDM. In addition, women with risk factors for GDM also underwent a 75 g OGTT regardless of the result of the OGCT.

Results: A positive 50 g OGCT was obtained in 123 (23%) of the women. In 15 (12%) of these, a diagnosis of GDM was established by the subsequent OGTT. Out of the 409 remaining women with a normal OGCT, 148 (36%) had risk factors for GDM. An OGTT performed in these patients identified 4 additional women with a GDM. Seventy-nine percent of GDM was thus found with 50g OGCT without regarding risk factors. Forty-seven percent of the women with GDM would have been missed in screening by risk factors only.

Conclusions: In our population 50 g OGCT appears to identify a higher number of GDM than risk factor based screening. Combined with risk factor screening a few more cases of GDM would be found.