Glucose (a type of sugar) is the body's main energy source, and hormones (such as insulin and glucagon) control the level of glucose in the blood. Hypoglycemia occurs when the level of glucose in the blood is lower than it should be.
It's a common problem in people being treated for diabetes. People with diabetes may experience hypoglycemia (also called a low blood sugar reaction) if they don't eat enough or if they take too much glucose-lowering medication (such as insulin). A person with hypoglycemia may feel hungry, shaky, sweaty, weak, drowsy, or dizzy. If left untreated, hypoglycemia may even lead to unconsciousness.