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.
Thus the working muscle can take in glucose even though little insulin is present. Another hormone from the pancreas, glucagon, stimulates the liver to release glucose to provide fuel for the muscles. The pancreas secretes two hormones, insulin and glucagon, to help maintain blood glucose levels.