Blood sugar (also known as blood glucose) is the sugar that the bloodstream carries to all cells in the body to supply us with energy. The sugar comes from the food we eat. Your blood sugar levels change throughout the day and are typically at their lowest point before your first meal. After you eat, the body responds by secreting insulin, a hormone produced by the pancreas that allows your body to either use the glucose from your food, or store it for future use. Insulin regulates your blood sugar levels, and tries to prevent them from getting too high or too low.