I think when blood sugar levels are high the pancreas secretes insulin to decrease sugar levels and restore homeostasis. Insulin and glucagon are hormones secreted by the islet cells of the pancreas. The are both secreted in response to blood sugar levels, but in opposite fashion. High blood glucose triggers secretion of insulin by the pancreas, such that in response the cells including muscle, red blood cells, and fat cells, by absorbing glucose out of the blood, thus lowering the high blood glucose levels to normal range.