Enzyme deficient in diabetes mellitus is:
**Core Concept**
Diabetes mellitus is a metabolic disorder characterized by hyperglycemia due to insulin deficiency or insulin resistance. The enzyme deficient in diabetes mellitus plays a crucial role in glucose metabolism and insulin signaling.
**Why the Correct Answer is Right**
Glucokinase is an enzyme that catalyzes the first step in glycolysis, converting glucose into glucose-6-phosphate. In diabetes mellitus, the activity of glucokinase is reduced, leading to impaired glucose uptake in the liver and increased glucose levels in the blood. This enzyme is particularly important in pancreatic beta cells, where it helps regulate glucose-stimulated insulin secretion. The deficiency of glucokinase is a key factor in the development of diabetes mellitus.
**Why Each Wrong Option is Incorrect**
**Option A:** Glucose-6-phosphatase is actually involved in gluconeogenesis and glycogenolysis, and its deficiency leads to glycogen storage disease type I, not diabetes mellitus.
**Option B:** Glucose-6-phosphate dehydrogenase is an enzyme involved in the pentose phosphate pathway, and its deficiency leads to hemolytic anemia, not diabetes mellitus.
**Option C:** Hexokinase is an enzyme that catalyzes the same reaction as glucokinase, but it is not specific to pancreatic beta cells and is not deficient in diabetes mellitus.
**Clinical Pearl / High-Yield Fact**
Glucokinase is a key enzyme in glucose sensing and insulin secretion, and its deficiency is a major contributor to the development of diabetes mellitus. Understanding the role of glucokinase in glucose metabolism is essential for managing diabetes and developing new treatments for this condition.
**Correct Answer:** D. Glucokinase