Which of the following statements is correct? a) Insulin suppresses the activity of glycogen synthase
b) Insulin mediates glucose uptake in the brain
c) "Prediabetes" is a condition characterized by an increased risk for the future development of type 2 diabetes
d) The rise in insulin concentration after meal ingestion is reduced in type 1 but not in type 2 diabetes

C) Prediabetes is a condition characterized by an increased risk for the future development of type 2 diabetes.

Explanation:

Prediabetes is a condition where there's a higher than normal blood sugar level but not high enough to be classified as type 2 diabetes. It is most likely to progress to type 2 diabetes if there are no lifestyle changes to mitigate the risk.

This progression can be stopped if the necessary lifestyle changes such as physical exercise, eating a healthy diet, weight control etc, are implemented.

Prediabetes doesn't usually present with any signs and symptoms though one possible sign is the darkening of the skin on the neck, armpit and elbows.

When signs like frequent urination, excessive thirst and fatigue are noticed, it is most likely the onset of type 2 diabetes.