Gestational diabetes mellitus (GDM) is best described as glucose intolerance diagnosed during which period?

• A. Before pregnancy
• B. During pregnancy
• C. After delivery
• D. During lactation

Answer: (B)

Gestational diabetes mellitus is defined by glucose intolerance that is first recognized during pregnancy. The timing matters because if glucose problems exist before conception, that is called pregestational diabetes, not GDM. If glucose intolerance appears or is diagnosed only after delivery, it would not be considered gestational diabetes. During pregnancy, hormonal changes—such as insulin resistance caused by placental hormones—can overwhelm the pancreas’s ability to keep blood glucose in check, leading to glucose intolerance that is identified in the prenatal period. Screening typically occurs in mid-pregnancy to catch these cases early and reduce risks to both mother and baby.