Glucose levels refer to the amount of glucose, a type of sugar, present in the blood. Glucose is a primary source of energy for the body's cells and is essential for proper functioning. Normal glucose levels typically range from 70 to 100 mg/dL when fasting. Monitoring glucose levels is crucial for individuals with conditions like diabetes, as abnormal levels can lead to serious health issues. High glucose levels, known as hyperglycemia, can cause symptoms like increased thirst and frequent urination, while low levels, or hypoglycemia, can lead to dizziness and confusion. Regular testing helps maintain healthy glucose levels.