**Core Concept**
Glucosuria, the presence of glucose in urine, can be an indicator of various conditions, including gestational diabetes mellitus (GDM). During pregnancy, the pancreas produces more insulin to meet the increased metabolic demands, but in some cases, it may not be sufficient, leading to hyperglycemia and subsequently glucosuria.

**Why the Correct Answer is Right**
The presence of glucosuria during an antenatal visit necessitates a diagnosis of gestational diabetes mellitus (GDM). This is because glucose is normally reabsorbed by the renal tubules, but in the presence of hyperglycemia, glucose spills over into the urine. GDM is a significant concern in pregnancy as it can lead to complications such as macrosomia, polyhydramnios, and increased risk of cesarean delivery. A diagnosis of GDM requires further evaluation, including a 50g glucose screening test followed by a 100g glucose tolerance test if the screening test is positive.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not directly related to the presence of glucosuria during an antenatal visit. While preeclampsia is a significant concern in pregnancy, it is not directly related to glucosuria.

**Option B:** This option is incorrect as glucosuria is not a direct indicator of preeclampsia. Preeclampsia is characterized by hypertension and proteinuria, not glucosuria.

**Option C:** This option is not relevant to the presence of glucosuria during an antenatal visit. While anemia is a common condition in pregnancy, it is not directly related to glucosuria.

**Clinical Pearl / High-Yield Fact**
A diagnosis of gestational diabetes mellitus (GDM) requires a 50g glucose screening test followed by a 100g glucose tolerance test if the screening test is positive. It is essential to diagnose GDM early in pregnancy to prevent complications and ensure optimal maternal and fetal outcomes.

**Correct Answer: C. Anemia.**