A 26-week pregnant patient has a 50-g oral glucose challenge with 1-hour glucose of 150 mg/dL. What is the appropriate next step?

• A. This confirms diabetes mellitus; give insulin.
• B. This confirms diabetes mellitus; dietary intake of carbohydrates should be lessened.
• C. This is suspicious of diabetes mellitus; an oral glucose tolerance test should be performed.
• D. This is an expected glucose level in a pregnant woman.

Answer: (C)

Screening with a 50-gram glucose challenge is used to identify risk for gestational diabetes, not to diagnose it. A 1-hour value of 150 mg/dL at 26 weeks is above common screening cutoffs, so it raises suspicion but does not confirm diabetes. The proper next step is to perform a diagnostic oral glucose tolerance test using a 100-gram glucose load after an overnight fast. The diagnosis of gestational diabetes is made based on the results of that test, typically requiring multiple abnormal values. Only after that confirmation would treatment decisions (such as dietary changes or insulin) be guided. This level is not considered a normal expected glucose in pregnancy.