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Taking too much insulin or not eating properly can cause low blood sugar in a person with diabetes.

Hypoglycemia is an extremely low level of glucose in the bloodstream. It can occur when a person with diabetes takes too much insulin or doesn't eat properly, especially before exercise.

People who experience hypoglycemia may be sweating, shaking, weak, nervous, dizzy or light-headed. They also may have a headache or be hungry.

If not treated in time, hypoglycemia can cause you to slip into a coma or have a seizure, according to the American Diabetes Association. For elderly people with cardiovascular problems, a hypoglycemic episode could lead to fainting or a fall. Hypoglycemia is life-threatening any time you can't treat yourself.

Glucose tablets or gel, fruit juice or food with a high sugar content can help you recover from hypoglycemia. In some cases, emergency medical treatment may be needed.

Reviewed 6/27/2025