Fruits and vegetables contain soluble and insoluble fiber in varying proportions. When you eat soluble fiber, it absorbs water to form a gel-like mass, which helps you feel full and provides other health benefits. It prevents a surge in blood sugar after you eat by slowing down the absorption of carbohydrates.
If the blood glucose level falls to dangerous levels (as in very heavy exercise or lack of food for extended periods), the Alpha cells of the pancreas release glucagon, a hormone whose effects on liver cells act to increase blood glucose levels.
Insulin is a hormone produced by the pancreas that controls glucose levels in blood by reducing the amount of glucose made by the liver and by increasing the removal of glucose from the blood by muscle and fat tissues. As a result, insulin causes blood glucose levels fall.