Glucagon increases glycemia and insulin reduces it. They are antagonistic pancreatic hormones. Glucagon acts stimulating glycogenolysis and thus forming glucose from glycogen breaking. Insulin is the hormone responsible for the entrance of glucose from the blood into the cells.
When glycemia is low, for example, during fasting, glucagon is secreted and insulin is inhibited. When glycemia is high, as after meals, there are inhibition of glucagon and more secretion of insulin.
