Glucose challenge test for detecting gestational diabetes mellitus: a systematic review

Background The best strategy to identify women with gestational diabetes mellitus (GDM) is unclear. Objectives To perform a systematic review to calculate summary estimates of the sensitivity and specificity of the 50-g glucose challenge test for GDM. Search strategy Systematic search of MEDLINE, EMBASE and Web of Science. Selection criteria Articles that compared the 50-g glucose challenge test with the oral glucose tolerance test (OGTT, with a 75-or 100-g reference standard) before 32 weeks of gestation. Data collection and analysis Summary estimates of sensitivity and specificity, with 95% confidence intervals and summary receiver operating characteristic curves, were calculated using bivariate random-effects models. Two reviewers independently selected articles that compared the 50 g glucose challenge test to the oral glucose tolerance test (OGTT, 75 or 100 gram, reference standard) before 32 weeks of gestation. Main results Twenty-six studies were included (13 564 women). Studies that included women with risk factors showed a pooled sensitivity of the 50-g glucose challenge test of 0.74 (95% CI 0.620.87), a pooled specificity of 0.77 (95% CI 0.66-0.89) (threshold value of 7.8 mmol/l), a derived positive likelihood ratio (LR) of 3.2 (95% CI 2.0-5.2) and a negative LR of 0.34 (95% CI 0.220.53). In studies with consecutive recruitment, the pooled sensitivity was 0.74 (95% CI 0.62-0.87) for a specificity of 0.85 (95% CI 0.80-0.91), with a derived positive LR of 4.9 (95% CI 3.5-7.0) and negative LR of 0.31 (95% CI 0.20-0.47). Increasing the threshold for disease (OGTT result) increased the sensitivity of the challenge test, and decreased the specificity. Author's conclusions The 50-g glucose challenge test is acceptable to screen for GDM, but cannot replace the OGTT. Further possibilities of combining the 50-g glucose challenge test with other screening strategies should be explored.