Fasting glycaemia to simplify screening for gestational diabetes

Recommendations in Switzerland on screening for gestational diabetes endorse the International Association of Diabetes in Pregnancy Study Group consensus. As universal testing is time consuming and glucose loading is unpleasant, the recommendations include a simplification, not performing the glucose loading in women with fasting glycaemia <4.4 mmol/l. Our objective was to evaluate the diagnostic performance of this simplified strategy, compared with the complete test, in our population with a low prevalence of gestational diabetes.

We collected 2298 complete 75-g glucose tolerance tests. We simulated stopping the test, so avoiding the glucose loading and further glycaemia, if fasting glycaemia was <4.4 or ≥5.1 mmol/l.

Unselected pregnant women from Geneva and Basel, at 24-28 weeks of gestation.

We calculated the sensitivity, and the percentage of women who would avoid the complete test with the strategy based on fasting glycaemia.

The prevalence of gestational diabetes was 10.9% in our population. Among 251 women with gestational diabetes, fasting glycaemia was ≥5.1 mmol/l in 119 women (47.4%), between 4.4 and <5.1 mmol/l in 78 women (31.1%) and <4.4 mmol/l in 54 women (21.5%). Proceeding with the complete test only in women with fasting glycaemia between 4.4 and <5.1 mmol/l will result in a sensitivity of 78.5%. This strategy would avoid glucose loading in 63.8% of women.

Screening with fasting glycaemia is an attractive alternative to universal screening with the complete 75-g glucose tolerance test. This strategy is, however, slightly less sensitive than previously reported in higher-risk populations.

Fasting glycaemia can be considered as an alternative to the complete test for gestational diabetes screening.