 Gestational Diabetes Screening
should be performed between 24 and 28 weeks in those women
not known to have glucose intolerance earlier in pregnancy.

🔹This evaluation is usually done in two steps. In the two-step
procedure, a 50-g oral glucose challenge test is followed by a
diagnostic 100-g oral glucose tolerance test (OGTT) if initial
results exceed a predetermined plasma glucose concentration.

🔹Plasma glucose level is measured 1 hour after a 50-g glucose
load without regard to the time of day or time of last meal.

🔹 A value of  140 mg/dL (7.8 mmol/L) identifies 80 percent of all
women with gestational diabetes.

🔹 Using a value of  130
mg/dL (7.2 mmol/L) increases the yield to greater than 90 percent.

🔹However, 20 to 25 percent of women will have false positive
test results compared with only 14 to 18 percent when the
 140 mg/dL cutoff value is used.