Universal two-step screening strategy for gestational diabetes has weak relevance in French Mediterranean women: should we simplify the screening strategy for gestational diabetes in France?

Aim: Currently, there is no international consensus for gestational diabetes mellitus (GDM) diagnosis. This is a report of our experience of GDM screening according to the 1996 French guidelines.

Methods: For 5 years, all pregnant women followed at our hospital (n=11,545) were prospectively screened for GDM between weeks 24 and 28 of pregnancy with a two-step strategy: the O'Sullivan test (OS) with a threshold at 130 mg/dL, followed by a 100-g OGTT if positive. GDM was diagnosed according to Carpenter and Coustan criteria.

Results: Prevalence of GDM was 4.26% [344/1451 of patients with an OS of 130-199 mg/dL (12.1%); and 148 patients with an OS greater than 200 mg/dL]. The false-positive rate for the OS was 76.8%. Compared with 140 mg/dL, a threshold of 130 mg/dL caused 401 additional negative OGTTs in 90% of cases. In 80.7% GDM patients, fasting glucose was less than 95 mg/dL. The time lag between OS and OGTT was 3 weeks (1-84 days). Risk factors associated with GDM were maternal age, preconception overweight and obesity, parity, personal history of GDM or macrosomia, and familial history of obesity (P<0.05), but not diabetes. Also, 20% of GDM patients had no risk factors, whereas they were present in 75% of patients without GDM.

Conclusion: In our population, a two-step screening strategy for GDM was neither relevant nor efficient. It could be simplified with a single-step definitive screening strategy using a 75-g OGTT, as used in the HAPO study, and as recommended by the IADPSG and the recent French Expert Consensus. At present, there are still no evidence-based arguments to help in deciding between selective or universal screening for GDM.