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In a healthy body, insulin helps glucose (sugar) get from the blood into the body's cells. There, the cells can use the sugar to make energy. However, when there is not enough insulin in the body, or if a person's body does not react to insulin normally (this is called insulin resistance), too much sugar stays in the blood. This can cause serious health problems.
Extremely high blood sugar means diabetes mellitus, a condition that often causes very high blood sugar. Hyperglycemia that comes and goes may mean diabetes of any kind, or may be developing under low insulin levels or resistance to insulin.
Three of the early signs of hyperglycemia are "the 3 polys": polydipsia (feeling very thirsty), polyphagia (feeling very hungry), and polyuria (urinating a lot). These things happen because:
- The body senses that its cells are not getting enough sugar. The body triggers hunger, because eating is usually how people get sugar. This causes polyphagia.
- The body senses that there is too much sugar in the blood, and tries to urinate out the extra sugar. This causes polyuria.
- Because the person is urinating so much, they get dehydrated easily and get very thirsty (polydipsia).
Other early signs of high blood sugar include blurred vision, headache, and feeling tired.
Symptoms of diabetic ketoacidosis can include: