Glucagon and Insulin are both hormones that regulate blood sugar levels and they are both produced by the pancreas.
When sugar levels in the blood are high the pancreas secretes insulin from its beta cells and releases it into the blood stream. Insulin causes the red blood cells, fat cells and muscle cells to absorb sugar from the blood .
When sugar levels are low, the pancreas secrets glucagon from its alpha cells which stimulates the liver to release the glucose that is stored in its cells.
Thus these two hormones work in the body to keep sugar levels balanced.