Accuracy of 50-g glucose challenge test to detect International Association of Diabetes and Pregnancy Study Groups criteria-defined hyperglycemia.

Objectives: To determine the accuracy of the 50-g glucose challenge test (GCT) in detecting hyperglycemia in pregnancy (HIP) across a range of glucose thresholds relative to the International Association of Diabetes and Pregnancy Study Groups diagnostic criteria, and to determine the accuracy of the 50-g GCT among patients with different risk status.

Methods: The present prospective cohort study included women aged 18-45 years at 24-31  weeks of pregnancy who presented at the Mother and Child Hospital, Akure, Nigeria, between September 1, 2015, and February 29, 2016. Patients underwent the 50-g GCT followed by the 75-g oral glucose tolerance test (OGTT). The accuracy of different 50-g GCT thresholds in diagnosing HIP was assessed based on International Association of Diabetes and Pregnancy Study Groups diagnostic criteria, with the 75-g OGTT used as a clinical reference standard.

Results: Of 280 patients enrolled, 46 (16.4%) had HIP. The sensitivity of the 50-g GCT to detect HIP decreased from 47.8% (95% confidence interval [CI], 32.9-63.1) at a 7.2-mmol/L threshold to 32.6% (95% CI, 19.5-48.0) at a 8.0-mmol/L threshold; the specificity improved from 84.2% (95% CI, 78.9-88.6) to 95.3% (95% CI, 91.7-97.6), respectively.

Conclusion: The 50-g GCT performed poorly compared with the 75-g OGTT for detecting HIP. It appears to be an unsuitable replacement for the 75-g OGTT.