**Core Concept**
The management of diabetes in pregnancy involves optimizing blood glucose control to prevent complications in both the mother and the fetus. This requires a comprehensive approach, including dietary modifications, physical activity, and medical therapy.

**Why the Correct Answer is Right**
In a newly diagnosed pregnant woman with diabetes, the first step in management is to assess the severity of the condition using a 50-gram glucose challenge test (GCT) or a casual plasma glucose test. This helps to determine if the woman has gestational diabetes mellitus (GDM), impaired glucose tolerance, or pre-existing diabetes. The results of this test will guide further management, including the need for more definitive testing, such as a 100-gram oral glucose tolerance test (OGTT), and initiation of treatment.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not address the need for initial assessment of the severity of diabetes in pregnancy.
**Option B:** This option is incorrect because it implies that treatment should be initiated immediately without assessing the severity of the condition.
**Option C:** This option is incorrect because it does not mention the need for initial assessment or testing to determine the severity of diabetes in pregnancy.

**Clinical Pearl / High-Yield Fact**
It is essential to note that the American College of Obstetricians and Gynecologists (ACOG) recommends that all pregnant women, regardless of risk factors, undergo a 50-gram glucose challenge test at 24-28 weeks of gestation to screen for gestational diabetes mellitus.

**Correct Answer: C. Assess the severity of the condition using a 50-gram glucose challenge test.**