Hyperglycemia occurs when you have a higher than usual level of glucose in your blood. This can happen shortly after you have eaten a big meal and is not a problem if your glucose level returns to normal. Cells remove glucose from the blood in response toinsulin. If your pancreas doesn't make enough insulin, glucose can't enter the cells and remains in the blood. Blood glucose levels can also get too high if cells areunable to respond to insulin properly (insulinresistance). Without glucose, your cells are unable to make energy and can't function properly.