In Step 1 of the two-step GDM screening, what 1-hour plasma glucose threshold prompts proceeding to Step 2?

• A. 120 mg/dL
• B. 125 mg/dL
• C. 130 mg/dL
• D. 140 mg/dL

Answer: (C)

In this screening approach, the first test is a non-fasting 50 g glucose challenge. You measure the blood glucose value 1 hour after the glucose load to decide who needs the more definitive test. The threshold that triggers moving on to the diagnostic step is 130 mg/dL. If the 1-hour result is at or above this level, the patient proceeds to Step 2, which is the 100 g, 3-hour oral glucose tolerance test performed after an overnight fast. This threshold is chosen to balance catching those at risk with not over-testing, because a lower cutoff increases sensitivity and brings more women to the confirmatory test. The Step 2 test then uses specific diagnostic criteria to determine whether gestational diabetes is present.