Main Organiser

Julius Centre University of Malaya

Co-organiser

Department of Social and Preventive Medicine, Faculty of Medicine, University of Malay

Supported by

University of Malaya

TAILORING GCT THRESHOLDS ACCORDING TO RISK

Author

Gill PK, Choo WY

Institution

University Malaya

Abstract

Objectives: Glucose challenge test (GCT) is a screening test for gestational diabetes, routinely practiced in a teaching hospital in Malaysia. The aim was to determine a GCT threshold value in low risk women and to determine an appropriate threshold value that is diagnostic of gestational diabetes.

Methods: A cross sectional retrospective analysis of 947 patient records was performed with the primary outcome being gestational diabetes based on the 2 hour 75g glucose tolerance test. The sensitivities, specificities and predictive values were compared for cutoff values between 7.2 and 7.8mmol/L.

Results: A threshold of 7.5mmol/L has Sn 88%, Sp 23% and PPV 23.7% for women with low risk for GDM. A blood glucose value of 10.8 mmol/L has specificity of 99.7% and PPV of 94.1% while 14.5mmol/L has 100% specificity.

Conclusion: A higher GCT threshold can be used to screen women at low risk of gestational diabetes and reduce the number requiring OGTT by 16% while maintaining a high detection rate. Although GCT was designed to be a screening test, diagnosis of GDM can be made when the blood sugar level exceeds 11mmol/L.