Which of the following has highest glycemic index?
**Core Concept**
The glycemic index (GI) is a measure of how quickly the carbohydrates in a particular food raise blood sugar levels. It is an important concept in the management of diabetes mellitus and for individuals with glucose intolerance. Foods with a high GI cause a rapid increase in blood glucose levels, whereas those with a low GI cause a gradual increase.
**Why the Correct Answer is Right**
Glucose itself has the highest glycemic index, as it is rapidly absorbed and causes a quick increase in blood glucose levels. This is because glucose is a simple sugar that can be directly absorbed into the bloodstream without any significant delay. The GI of glucose is set at 100, and all other foods are compared to it. The rapid increase in blood glucose levels after consuming glucose can be attributed to its ability to readily cross the intestinal epithelial cells and enter the bloodstream.
**Why Each Wrong Option is Incorrect**
* **Option A:** Foods like white bread and refined sugars have a high glycemic index due to their rapid digestion and absorption. However, they do not have the highest GI, which is held by glucose itself.
* **Option B:** Fruits like bananas and apples have a moderate glycemic index due to their complex carbohydrate content and fiber. They do not have the highest GI, which is held by glucose itself.
* **Option C:** Complex carbohydrates like whole grains and legumes have a low glycemic index due to their slow digestion and absorption. They do not have the highest GI, which is held by glucose itself.
**Clinical Pearl / High-Yield Fact**
When managing diabetes mellitus, it is essential to choose foods with a low to moderate glycemic index to prevent rapid spikes in blood glucose levels. Foods with a high GI should be avoided, especially in patients with poorly controlled diabetes.
**Correct Answer:** D. Glucose.