Development of a modified 100-gram oral glucose tolerance test for diagnosis of gestational diabetes mellitus and its diagnostic accuracy

To develop a modified 100-g oral glucose tolerance test (100-g OGTT) for the diagnosis ofgestational diabetes mellitus (GDM) in order to reduce the number of values needed for the test. Patient charts ofpregnant women who completed the 100-g OGT test at the antenatal clinic, Siriraj Hospital between 2005 and 2006 were reviewed. Cases diagnosed with GDM using standard 100-g OGTT were selected. In non-GDM cases, the last 100-g OGTT test was selected. Diagnostic performances of each glucose value and two or three values in various combinations were determined. One thousand seven hundred sixty three women completed GDM diagnosis throughout their pregnancy Four hundred three women had GDM while 1360 subjects were non-GDM. Considering single glucose values, the highest level of accuracy, and the best ROC curve were obtained from the value at 2 hours after glucose ingestion (2-h glucose value) with 93.00% accuracy and the area under the ROC curve of 0.961. The combination of 2-h glucose value with fasting plasma glucose (FPG) showed 93.25% accuracy. FPG combined with 1-h and 2-h glucose values achieved 100% sensitivity with 92% accuracy. FPG in combined with 1-h and 2-h glucose values is an interesting alternative for the diagnosis of GDM.