Now, another reason might be because we fast, we don't eat for a very long period of time. So if we don't eat for a long time, the cells of our body will use up the majority of the glucose in our blood to produce ATP, to use it for energy, and that can lower the concentration of glucose inside our blood. And that will ultimately lead to hypoglycemia. Now, hypoglycemia can be very dangerous because our brain, for example, uses glucose as the main energy source. So if we don't have enough glucose inside our blood, that can basically damage our brain cells, because the brain cannot use glucose if there is no glucose inside our blood. So let's move on to the second type of abnormality known as hyperglycemia.