Hyperglycemia is a medical term that refers to high levels of glucose, or sugar, in the blood. This condition often occurs in people with diabetes, a disease that affects how the body processes sugar. When blood sugar levels rise above normal, it can lead to symptoms such as increased thirst, frequent urination, and fatigue. If left untreated, hyperglycemia can lead to serious complications, including diabetic ketoacidosis or long-term damage to organs like the heart and kidneys. Managing blood sugar levels through diet, exercise, and medication is essential for those at risk of hyperglycemia.