Question

Which among the following is NOT a cause of fasting hypoglycemia?

• A. Glucagon excess
• B. Glucose-6-phosphatase deficiency
• C. Cirrhotic liver damage
• D. Glycogen synthase deficiency

Hint:

Which listed factor would raise, not lower, blood glucose?

Answer 1

The Correct Option is A

Step 1: Fasting hypoglycemia results when the liver cannot maintain blood glucose between meals, i.e. when glycogenolysis or gluconeogenesis fails or when glucose-raising counter-regulation is lost.
Step 2: Glucagon is the principal hyperglycemic hormone; an excess of glucagon raises blood glucose, so glucagon excess causes hyperglycemia, not hypoglycemia. It cannot be a cause of fasting hypoglycemia.
Step 3: Check the others. Glucose-6-phosphatase deficiency (von Gierke disease, GSD I) prevents release of free glucose from the liver, causing severe fasting hypoglycemia. Cirrhotic liver damage depletes glycogen stores and impairs gluconeogenesis, causing fasting hypoglycemia. Glycogen synthase deficiency (GSD 0) means little hepatic glycogen is stored, so glucose cannot be supplied during fasting, again causing fasting hypoglycemia.
Step 4: The one option that does not cause fasting hypoglycemia is glucagon excess.
Conclusion: The answer is glucagon excess, option A, matching the printed key.