Behavioral Signs of Low Blood Sugar

Low blood sugar, also known as hypoglycemia or low blood glucose, is a condition that occurs when the glucose level in the blood falls below normal. The vast majority of hypoglycemia occurs in people with diabetes, and is a result of the medication or insulin used for treatment 12. While blood glucose testing is the only way to definitively diagnose this condition, there are many behavioral signs that may indicate a person is experiencing hypoglycemia.

Early Behavioral Symptoms

The onset of hypoglycemia can be sudden 12. Early behavioral signs are generally mild and may be difficult to notice. People experiencing low blood sugar may appear shaky or act nervous. They may complain of hunger or look pale and sweaty. These symptoms result from a central nervous system response to low blood glucose levels. Recognizing and responding to these symptoms is important because the body, especially the brain, depends on glucose as its main source of energy to function.

Late Behavioral Symptoms

If early symptoms of low blood sugar are not recognized and treated, behavioral signs can progress. This is due to a lack of adequate glucose for the brain. The hypoglycemic person may feel lightheaded, weak, dizzy or tired. He may seem confused or have difficulty concentrating. Others might notice that the person is slurring his speech or having mood swings, with possible crying or aggression. Sometimes these behaviors are mistaken for alcohol intoxication.

Hypoglycemia Unawareness

Some people with low blood sugar may experience no early behavioral signs. This condition, called hypoglycemia unawareness, occurs when there are frequent episodes of low blood sugar. The body becomes used to the low blood sugar levels and no longer reacts in a normal way. This condition can be dangerous because the early behavior signs are absent, thus preventing the low blood sugar from being identified and treated before it becomes severe.

Low Blood Sugar During Sleep

Hypoglycemia during sleep, or nocturnal hypoglycemia, occurs most often in people with type 1 diabetes 2. While sleeping, a person with low blood sugar may have vivid nightmares or cry out. Upon waking, a person with nocturnal hypoglycemia may be irritable, confused or excessively tired. Because the behavioral signs of nocturnal hypoglycemia are not obvious and are different from those exhibited during waking hours, this condition is frequently not identified.


Regardless of when they occur, report any behavioral signs of low blood sugar to your health care provider for further evaluation. If low blood sugar is severe and left untreated, symptoms can progress to seizures, loss of consciousness, brain damage and even death.