Glucose is a simple sugar and an essential carbohydrate that serves as a primary energy source for living organisms. It is a monosaccharide, meaning it cannot be broken down into simpler sugars. Glucose is crucial for cellular respiration, where it is metabolized to produce energy in the form of ATP. In the human body, glucose levels are tightly regulated by hormones such as insulin and glucagon. High or low levels of glucose can lead to health issues, including diabetes and hypoglycemia. Foods rich in carbohydrates, like fruits and grains, are significant sources of glucose, making it vital for a balanced diet.