Methods of screening for and diagnosing of gestational diabetes

Screening for gestational diabetes should be performed using a 50-g 1-hour glucose challenge. The threshold for further testing may be chosen based on the goal of the screening program, either to maximize sensitivity at the expense of more diagnostic testing by using a 130 mg/dL cutoff or to increase specificity at the sacrifice of some sensitivity by using a 140 mg/dL cutoff. The choice of universal screening or an age cutoff, such as 25 years, with testing reserved in younger women for those with risk factors, is dependent on the characteristics of a given patient population or practice. The diagnostic test for gestational diabetes is the 100-g 3-hour oral glucose tolerance test on venous plasma or serum specimens. Whole blood values may be used, but the use of capillary blood measurements by test strips and reflectance meters is not recommended.