[Prevalence of gestational diabetes in high-risk pregnancies: screened using an oral glucose tolerance test]

To determine the prevalence of gestational diabetes mellitus in high-risk pregnancies during the second or third trimester diagnosed by screening with the 75-gram oral glucose tolerance test (75 g-OGTT) and, to determine the prevalence of the need for insulin therapy after an initial dietary intervention.

Prospective cohort study.

Pregnant women at high-risk for gestational diabetes mellitus were challenged with the 75 g-OGTT in the second or third trimester, ideally between the 24th and the 28th week of pregnancy. The diagnosis of gestational diabetes mellitus was established when the fasting plasma glucose was ≥ 7.0 mmol/l or when the plasma glucose was ≥ 7.8 mmol/l two hours after the oral ingestion of 75 g glucose. The women with gestational diabetes were initially treated with a dietary regime. Insulin treatment was added if the hyperglycaemia persisted.

A total of 471 pregnant women were included. Of these women, 75.8% underwent the 75 g-OGTT between the 24th and 28th week of pregnancy; 24.2% underwent the test between the 28th and 35th week. The diagnosis of gestational diabetes mellitus was established in 24.2% of the pregnant women. Dietary intervention was successful in normalising the blood glucose levels in 77.2% of the cases. The remaining 22.8% needed the additional insulin treatment.

We ascertained that the prevalence of gestational diabetes mellitus in high-risk pregnancies was high. In most cases, the gestational diabetes mellitus could be managed by diet. A multidisciplinary approach involving obstetricians, gynaecologists, dieticians and internists is needed to ensure a timely diagnosis and adequate treatment during pregnancy.