Improved gestational diabetes screening protocol

OBJECTIVES: This work aimed to assess the diagnostic validity of two approaches for the screening of gestational diabetes mellitus (GDM) with less discomfort for pregnant women. METHODS: A prospective diagnostic validation study was conducted with 2007 pregnant women. According to risk factors for GDM, women were classified into high-risk and low-risk groups. The current diagnostic procedure, based on oral glucose overload, was followed; simultaneously HbA(1c) was tested and an algorithm combining both biomarkers was applied. RESULTS: In the low-risk group, the Glucose challenge test (GCT) showed a higher area under the curve (AUC 0.953; 95% CI 0.915–0.992) than the HbA(1c) test (0.688; 95% CI 0.541–0.834). The best GCT cut-off, 153.5 mg/dL (8.52 mmol/L), showed higher diagnostic validity than that for HbA(1c), 28 mmol/mol (4.75%), and that the algorithm using both tests. In the high-risk group, the GCT showed better diagnostic performance than the HbA(1c) and the algorithm; the optimal GCT cut-offs were higher than those recommended in current protocols. 13th week: GCT AUC 0.882 (95% CI 0.843–0.921), HbA(1c) AUC 0.624 (95% CI 0.562–0.686), GCT cut-off 140.5 mg/dL (7.8 mmol/L), HbA(1c) cut-off 33 mmol/mol (5.15%). 24th week: GCT AUC 0.944 (95% CI 0.925–0.962), HbA(1c) AUC 0.642 (95% CI 0.575–0.709), GCT cut-off, 145.5 mg/dL (8.08 mmol/L), HbA(1c) cut-off 29 mmol/mol (4.85%). CONCLUSIONS: The GDM diagnostic approach using as the first step the GCT with higher cut-offs showed the best diagnostic validity. Applying these thresholds, 55.6 and 13.7% of 100 g. Oral glucose overloads would have been avoided in low-risk and high-risk pregnant women.