**Question:** Absorption of glucose in the intestine is by

**Core Concept:** Glucose absorption is a crucial process in the digestive system, where glucose molecules are taken up from the gastrointestinal tract into the bloodstream. The primary mechanisms for glucose absorption include passive diffusion and active transport.

**Why the Correct Answer is Right:** In the intestine, glucose absorption occurs primarily through sodium-dependent glucose transporter proteins (SGLTs), specifically SGLT1 and SGLT2. These transporters facilitate the active transport of glucose into the enterocytes (intestinal epithelial cells) against the concentration gradient. This active transport process ensures efficient glucose absorption and maintains glucose homeostasis.

**Why Each Wrong Option is Incorrect:**

A. **Passive diffusion:** While glucose may passively diffuse across cell membranes, the question specifically mentions active transport, indicating that passive diffusion is not the correct answer.

B. **SGLT2:** SGLT2 is responsible for reabsorption of glucose in the kidneys, not in the intestine.

C. **SGLT3:** SGLT3 is another glucose transporter, but it is primarily expressed in the central nervous system and not involved in glucose absorption in the intestine.

D. **Enterocytes:** While enterocytes are the cells responsible for glucose absorption, the correct answer focuses on the specific glucose transporters involved, namely SGLT1 and SGLT2.

**Clinical Pearl / High-Yield Fact:** Understanding glucose absorption is crucial for maintaining glucose homeostasis and preventing hyperglycemia. In conditions like type 2 diabetes, glucose absorption is disrupted, leading to hyperglycemia. This highlights the importance of understanding the correct mechanisms and proteins involved in glucose absorption for clinical application.

**Correct Answer:** D. Enterocytes

In summary, glucose absorption in the intestine occurs through enterocytes, which are the cells responsible for this process. However, the correct answer emphasizes the involvement of sodium-dependent glucose transporters SGLT1 and SGLT2 in facilitating active glucose transport across the intestinal epithelial cells. This understanding is essential for clinical application and managing conditions like diabetes, where glucose absorption mechanisms may be disrupted.