Hyperglycemia refers to a high blood glucose level. It occurs when there is an excess amount of glucose in the bloodstream, often due to the body's inability to produce or effectively use insulin. This condition is commonly associated with diabetes and can lead to various symptoms such as increased thirst, frequent urination, fatigue, and blurred vision. If left untreated, hyperglycemia can cause serious complications, including damage to the blood vessels, nerves, and organs. Therefore, it is important to manage blood glucose levels through proper diet, exercise, medication, and regular monitoring.