Insulin is a hormone secreted by the pancreas that plays a critical role in regulating blood sugar levels in the body. When we eat, the carbohydrates present in the food get broken down into glucose, which enters the bloodstream. As blood sugar levels rise, the pancreas secretes insulin, which enables the body's cells to take up glucose from the bloodstream and use it for energy. Insulin also helps to lower the amount of glucose produced by the liver. In people with diabetes, the body does not produce enough insulin or cannot use it properly, resulting in high blood sugar levels.