In gestational diabetes screening, after a 50 g glucose load with 1-hour glucose of 150 mg/dL, what is the indicated next step?

• A. This confirms diabetes mellitus; 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)

A positive result on the 50 g glucose challenge test signals possible gestational diabetes, but it is not diagnostic by itself. The proper next step is to perform a diagnostic oral glucose tolerance test to confirm whether glucose intolerance meets the criteria for gestational diabetes. The OGTT involves measuring glucose after a fasting state followed by a glucose load (most commonly 100 g with multiple time points, or 75 g depending on the guideline). Only the OGTT results establish the diagnosis and guide management. Starting insulin or recommending substantial dietary restrictions aren’t appropriate until gestational diabetes is confirmed, and a 1-hour value of 150 mg/dL on the screening test is not itself an expected normal level in pregnancy.