The phrase "low blood sugar numbers" means the body contains less than 70 milligrams per deciliter of glucose in the bloodstream, according to Mayo Clinic. Low blood sugar, known as hypoglycemia, is an indication that a health problem or medication is depriving the body of sufficient energy stores. Lack of glucose interferes with body and brain functions, causing symptoms such as fatigue, heart palpitations, sweating, anxiety and shakiness.
The body produces glucose and extracts it from many foods to deliver energy to cells, KidsHealth states. Hypoglycemia is most common in people with diabetes because they use insulin treatments to help the body carry glucose from the bloodstream to cells. Diabetics can upset the balance of glucose and insulin in their bodies by making seemingly minor changes in diet or physical activity, such as skipping meals or exercising longer without eating adequate meals.
When the body digests glucose, it stores a backup supply as glycogen to help stabilize energy levels, Mayo Clinic explains. A decrease in blood sugar levels stimulates the release of glucagon, a hormone that tells the liver to break down the stored glycogen to increase the amount of glucose in the bloodstream. This process helps the body fuel itself when people skip meals or take long breaks between meals. However, if hypoglycemia develops and persists, the condition may cause serious symptoms, such as seizures, confusion, blurred vision or loss of consciousness.