How does my body control blood sugar levels?

Gets sugar in cells. Hormones, like Insulin and glucagon regulate sugar levels. Reserves, like carbohydrates and fat, get broken down, and ultimately ends up in the blood as glucose, which supplys the cells with the help of insulin. Exercise draws on this supply because the cells do more work, and so glucose is replaced by glucose through glucagon and other hormones until it is back to a sustainable level.