Time-dependent gestational diabetes screening values

This study was undertaken to determine use of different cut-off values with regard to the time of the patient's last meal in screening for gestational diabetes mellitus which could result in better results and change patient management.

Two hundred and seventy-four non-diabetic women undergoing routine screening for glucose intolerance between 26 to 28 weeks' gestation were classified with regard to the time of previous meal. A glucose challenge test and an oral glucose challenge test were conducted for each patient in the study. Results were evaluated with both a standard cut-off value of 140 mg/dl without regard to the time of the last meal and suggested cut-off values of 148 mg/dl, 142 mg/dl, and 150 mg/dl if the patient ate < 2 h, 2-3 h, and > 3 h before the screening test, respectively.

Two hundred and seventy-four women completed the study. With these suggested cut-off values, the number of patients with a positive glucose challenge test dropped from 15.7% to 11.3%. With these cut-off values, positive predictive value increased from 27.3% to 32.3%.

The time since previous meal affects 50 g glucose challenge test results. These new cut-off values would lead to improved efficiency of the screening test and decreased frequency with which patients require the 3-h oral glucose tolerance test.