Question

A patient had dinner at 8 PM in the night and dose his blood sugar test at 7 AM in the morning. What is the major source of glucose

• A. Muscle Glycogen
• B. Liver Glycogen
• C. Gluconeogenesis
• D. Dietary Carbohydrate

Answer 1

The Correct Option is B

During periods of fasting, such as overnight fasting from 8 PM to 7 AM, the body's primary source of glucose to maintain blood sugar levels is liver glycogen. Here's a breakdown:

• Muscle Glycogen: Muscle glycogen is not typically used for increasing blood glucose during fasting, because it lacks the enzyme glucose-6-phosphatase, which is necessary to convert glycogen to free glucose that can be released into the bloodstream. It is primarily used for energy within muscle cells during physical activity.
• Liver Glycogen: The liver stores glycogen that can be readily broken down to glucose and released into the bloodstream to maintain normal blood sugar levels during fasting states. This process is essential overnight when no dietary carbohydrates are being consumed.
• Gluconeogenesis: This is the metabolic pathway through which glucose is synthesized from non-carbohydrate components like lactate, glycerol, and amino acids. While it becomes more significant during prolonged fasting, in the short overnight fasting period, liver glycogen is the primary source.
• Dietary Carbohydrate: This is relevant when food is consumed. Since the patient has not eaten since 8 PM, dietary carbohydrates are not contributing to blood glucose levels at 7 AM.

Thus, during the overnight fast, liver glycogen is the major source of blood glucose, preventing hypoglycemia and ensuring a continuous supply of energy to the body, especially the brain.