As per etiological classification of diabetes mellitus, Gestational diabetes mellitus is
**Core Concept**
Gestational diabetes mellitus (GDM) is classified etiologically as a category of diabetes mellitus that occurs or is first recognized during pregnancy. This category is distinct from type 1 and type 2 diabetes mellitus due to its unique pathophysiology and clinical presentation.
**Why the Correct Answer is Right**
GDM is characterized by insulin resistance and impaired insulin secretion in response to the increased metabolic demands of pregnancy. The insulin resistance is thought to be mediated by the placental production of various hormones, including human placental lactogen (hPL) and estrogen, which interfere with insulin signaling pathways. This results in impaired glucose tolerance, which can lead to hyperglycemia and the development of GDM. **Option C** is the correct answer as it accurately reflects the etiological classification of GDM.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect as it does not accurately reflect the etiological classification of GDM.
* **Option B:** This option is incorrect as it is a type of diabetes mellitus that is not specific to pregnancy.
**Clinical Pearl / High-Yield Fact**
GDM is a significant risk factor for developing type 2 diabetes mellitus in the future, and it is essential to screen women with a history of GDM for type 2 diabetes mellitus after pregnancy.
**Correct Answer:** C. Impaired insulin secretion and insulin resistance due to placental hormones.